1467 lines
100 KiB
HTML
1467 lines
100 KiB
HTML
<?xml version="1.0" encoding="utf-8"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
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"http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv=Content-Type content="text/html; charset=utf8">
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<title>Acme: A User Interface for Programmers</title>
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</meta>
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</head>
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<body>
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<p style="margin-top: 0; margin-bottom: 0.50in"></p>
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<p style="margin-top: 0; margin-bottom: 0.21in"></p>
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<p style="line-height: 1.4em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: center;">
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<span style="font-size: 12pt"><b>Acme: A User Interface for Programmers</b></span></p>
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<p style="margin-top: 0; margin-bottom: 0.21in"></p>
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<p style="margin-top: 0; margin-bottom: 0.17in"></p>
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<p style="line-height: 1.4em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: center;">
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<span style="font-size: 10pt"><i></i></span><span style="font-size: 10pt"><i>Rob Pike</i></span><span style="font-size: 10pt"><i></i></span></p>
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<p style="line-height: 1.4em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: center;">
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<span style="font-size: 10pt"><i></i></span><span style="font-size: 10pt"><i>rob@plan9.bell-labs.com</i></span><span style="font-size: 10pt"><i></i></span></p>
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<p style="margin-top: 0; margin-bottom: 0.17in"></p>
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<p style="margin-top: 0; margin-bottom: 0.08in"></p>
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<p style="margin-top: 0; margin-bottom: 0.33in"></p>
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<p style="line-height: 1.4em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: center;">
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<span style="font-size: 10pt"><i>ABSTRACT</i></span></p>
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<p style="margin-top: 0; margin-bottom: 0.19in"></p>
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<p style="margin-top: 0; margin-bottom: 0.17in"></p>
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<p style="margin-top: 0; margin-bottom: 0.17in"></p>
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<p style="margin-top: 0; margin-bottom: 0.17in"></p>
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<p style="line-height: 1.2em; margin-left: 1.50in; text-indent: 0.00in; margin-right: 1.50in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">A hybrid of window system, shell, and editor, Acme gives text-oriented
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applications a clean, expressive, and consistent style of interaction.
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Traditional window systems support interactive client programs and offer libraries of
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pre-defined operations such as pop-up menus
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and buttons to promote a consistent
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user interface among the clients.
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Acme instead provides its clients with a fixed user interface and
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simple conventions to encourage its uniform use.
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Clients access the facilities of Acme through a file system interface;
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Acme is in part a file server that exports device-like files that may be
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manipulated to access and control the contents of its windows.
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Written in a concurrent programming language,
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Acme is structured as a set of communicating processes that neatly subdivide
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the various aspects of its tasks: display management, input, file server, and so on.
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</span><span style="font-size: 10pt"></span><span style="font-size: 10pt"></span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
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<p style="line-height: 1.2em; margin-left: 1.50in; text-indent: 0.35in; margin-right: 1.50in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">Acme attaches distinct functions to the three mouse buttons:
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the left selects text;
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the middle executes textual commands;
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and the right combines context search and file opening
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functions to integrate the various applications and files in
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the system.
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</span><span style="font-size: 10pt"></span><span style="font-size: 10pt"></span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
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<p style="line-height: 1.2em; margin-left: 1.50in; text-indent: 0.35in; margin-right: 1.50in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">Acme works well enough to have developed
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a community that uses it exclusively.
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Although Acme discourages the traditional style of interaction
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based on typescript windows—teletypes—its
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users find Acme’s other services render
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typescripts obsolete.
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</span></p><p style="margin-top: 0; margin-bottom: 0.17in"></p>
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<p style="margin-top: 0; margin-bottom: 0.17in"></p>
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<p style="margin-top: 0; margin-bottom: 0.17in"></p>
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<p style="margin-top: 0; margin-bottom: 0.50in"></p>
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<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt"><b>History and motivation
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</b></span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
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<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">The usual typescript style of interaction with
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Unix and its relatives is an old one.
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The typescript—an intermingling of textual commands and their
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output—originates with the scrolls of paper on teletypes.
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The advent of windowed terminals has given each user what
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amounts to an array of teletypes, a limited and unimaginative
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use of the powers of bitmap displays and mice.
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Systems like the Macintosh
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that do involve the mouse as an integral part of the interaction
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are geared towards general users, not experts, and certainly
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not programmers.
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Software developers, at least on time-sharing systems, have been left behind.
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</span></p><center><table width=60% cellspacing=0 cellpadding=0 border=0><tr height=1> <td width=1 bgcolor=#000000 /> <td width=10 bgcolor=#000000 /> <td bgcolor=#000000 /> <td width=10 bgcolor=#000000 /> <td width=1 bgcolor=#000000 /></tr><tr height=10> <td width=1 bgcolor=#000000 /> <td width=10 /> <td /> <td width=10 /> <td width=1 bgcolor=#000000 /></tr>
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<tr>
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<td width=1 bgcolor=#000000 /><td width=10 /><td>
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<center><a href="acme.fig1.gif"><img src="acme.fig1.gif" /></a></center>
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<p style="line-height: 1.2em; text-indent: 0.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">Figure 1. A small Acme screen—normally it runs on a larger display—demonstrating
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some of the details discussed in the text.
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The right column contains some guide files,
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a mailbox presented by Acme’s mail program,
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the columnated display of files in Acme’s own source directory,
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a couple of windows from the OED browser,
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a debugger window,
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and an error window showing diagnostics from a compilation.
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The left column holds a couple of source files
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(</span><span style="font-size: 10pt"><tt>dat.h</tt></span><span style="font-size: 10pt">
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and
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</span><span style="font-size: 10pt"><tt>acme.l</tt></span><span style="font-size: 10pt">),
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another debugger window displaying a stack trace,
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and a third source file
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(</span><span style="font-size: 10pt"><tt>time.l</tt></span><span style="font-size: 10pt">).
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</span><span style="font-size: 10pt"><tt>Time.l</tt></span><span style="font-size: 10pt">
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was opened from the debugger by clicking the right mouse button
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on a line in the stack window;
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the mouse cursor landed on the offending line of
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</span><span style="font-size: 10pt"><tt>acme.l</tt></span><span style="font-size: 10pt">
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after a click on the compiler message.
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</span></p></td>
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<td width=10 /><td width=1 bgcolor=#000000 />
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</tr>
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<tr height=10><td width=1 bgcolor=#000000 /> <td width=10 /><td /><td width=10 /> <td width=1 bgcolor=#000000 /></tr><tr height=1> <td width=1 bgcolor=#000000 /> <td width=10 bgcolor=#000000 /> <td bgcolor=#000000 /> <td width=10 bgcolor=#000000 /> <td width=1 bgcolor=#000000 /></tr>
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</table></center>
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<p style="margin-top: 0; margin-bottom: 0.05in"></p>
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<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">Some programs have mouse-based editing of
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text files and typescripts;
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ones I have built include
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the window systems
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</span><span style="font-size: 10pt"><tt>mux</tt></span><span style="font-size: 10pt">
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[Pike88]
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and
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</span><span style="font-size: 10pt"><tt>8½</tt></span><span style="font-size: 10pt">
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[Pike91]
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and the text editor
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Sam [Pike87].
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These have put the programmer’s mouse to some productive work,
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but not wholeheartedly. Even experienced users of these programs
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often retype text that could be grabbed with the mouse,
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partly because the menu-driven interface is imperfect
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and partly because the various pieces are not well enough integrated.
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</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
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<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">Other programs—EMACS [Stal93] is the prime example—offer a high
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degree of integration but with a user interface built around the
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ideas of cursor-addressed terminals that date from the 1970’s.
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They are still keyboard-intensive and
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dauntingly complex.
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</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
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<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">The most ambitious attempt to face these issues was the Cedar
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system, developed at Xerox [Swei86].
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It combined a new programming language, compilers,
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window system, even microcode—a complete system—to
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construct a productive, highly
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integrated and interactive environment
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for experienced users of compiled languages.
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Although successful internally, the system was so large
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and so tied to specific hardware that it never fledged.
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</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
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<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">Cedar was, however, the major inspiration for Oberon [Wirt89],
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a system of similar scope but much smaller scale.
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Through careful selection of Cedar’s ideas, Oberon shows
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that its lessons can be applied to a small, coherent system
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that can run efficiently on modest hardware.
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||
In fact, Oberon probably
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||
errs too far towards simplicity: a single-process system
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with weak networking, it seems an architectural throwback.
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</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
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<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">Acme is a new program,
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a combined window system, editor, and shell,
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that applies
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some of the ideas distilled by Oberon.
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Where Oberon uses objects and modules within a programming language (also called Oberon),
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Acme uses files and commands within an existing operating system (Plan 9).
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Unlike Oberon, Acme does not yet have support for graphical output, just text.
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At least for now, the work on Acme has concentrated on
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producing the smoothest user interface possible for a programmer
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at work.
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</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
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<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">The rest of this paper describes Acme’s interface,
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explains how programs can access it,
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compares it to existing systems,
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and finally presents some unusual aspects of its implementation.
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</span></p><p style="margin-top: 0; margin-bottom: 0.17in"></p>
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<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt"><b>User interface
|
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</b></span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
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<center><table width=60% cellspacing=0 cellpadding=0 border=0><tr height=1> <td width=1 bgcolor=#000000 /> <td width=10 bgcolor=#000000 /> <td bgcolor=#000000 /> <td width=10 bgcolor=#000000 /> <td width=1 bgcolor=#000000 /></tr><tr height=10> <td width=1 bgcolor=#000000 /> <td width=10 /> <td /> <td width=10 /> <td width=1 bgcolor=#000000 /></tr>
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<tr>
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<td width=1 bgcolor=#000000 /><td width=10 /><td>
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<center><a href="acme.fig2.gif"><img src="acme.fig2.gif" /></a></center>
|
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<p style="line-height: 1.2em; text-indent: 0.35in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">Figure 2. An Acme window showing a section of code.
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The upper line of text is the tag containing the file name,
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relevant commands, and a scratch area (right of the vertical bar);
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the lower portion of the window is the
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body, or contents, of the file.
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Here the scratch area contains a command for the middle button
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(</span><span style="font-size: 10pt"><tt>mk</tt></span><span style="font-size: 10pt">)
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and a word to search for with the right button
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(</span><span style="font-size: 10pt"><tt>cxfidalloc</tt></span><span style="font-size: 10pt">).
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The user has just
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clicked the right button on
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</span><span style="font-size: 10pt"><tt>cxfidalloc</tt></span><span style="font-size: 10pt">
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and Acme has searched for the word, highlighted it,
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and moved the mouse cursor there. The file has been modified:
|
||
the center of the layout box is black and the command
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</span><span style="font-size: 10pt"><tt>Put</tt></span><span style="font-size: 10pt">
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appears in the tag.
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||
</span></p></td>
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<td width=10 /><td width=1 bgcolor=#000000 />
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</tr>
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<tr height=10><td width=1 bgcolor=#000000 /> <td width=10 /><td /><td width=10 /> <td width=1 bgcolor=#000000 /></tr><tr height=1> <td width=1 bgcolor=#000000 /> <td width=10 bgcolor=#000000 /> <td bgcolor=#000000 /> <td width=10 bgcolor=#000000 /> <td width=1 bgcolor=#000000 /></tr>
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</table></center>
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||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">Acme windows are arrayed in columns (Figure 1) and are used more
|
||
dynamically than in an environment like X Windows or
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</span><span style="font-size: 10pt"><tt>8½</tt></span><span style="font-size: 10pt">
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[Sche86, Pike91].
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The system frequently creates them automatically and the user
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can order a new one with a single mouse button click.
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The initial placement of a new window is determined
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automatically, but the user may move an existing window anywhere
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by clicking or dragging a
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</span><span style="font-size: 10pt"><i>layout box</i></span><span style="font-size: 10pt">
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||
in the upper left corner of
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||
the window.
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||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">Acme windows have two parts: a
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</span><span style="font-size: 10pt"><i>tag</i></span><span style="font-size: 10pt">
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||
holding a single line of text,
|
||
above a
|
||
</span><span style="font-size: 10pt"><i>body</i></span><span style="font-size: 10pt">
|
||
holding zero or more lines (Figure 2).
|
||
The body typically contains an image of a file being edited
|
||
or the editable output of a
|
||
program, analogous to an
|
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EMACS shell
|
||
window. The tag contains
|
||
the name of the window
|
||
(usually the name of the associated
|
||
file or directory), some built-in commands, and a scratch area to hold arbitrary text.
|
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If a window represents a directory, the name in the tag ends with
|
||
a slash and the body contains a list of the names of the files
|
||
in the directory.
|
||
Finally, each non-empty body holds a scroll bar at the left of the text.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Each column of windows also has a layout box and a tag.
|
||
The tag has no special meaning, although Acme pre-loads it with a few
|
||
built-in commands.
|
||
There is also a tag across the whole display, also loaded with
|
||
helpful commands and a list of active processes started
|
||
by Acme.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Typing with the keyboard and selecting with the left button are as in
|
||
many other systems, including the Macintosh,
|
||
</span><span style="font-size: 10pt"><tt>8½</tt></span><span style="font-size: 10pt">,
|
||
and Sam.
|
||
The middle and right buttons are used, somewhat like the left button,
|
||
to ‘sweep’ text, but the indicated text is treated in a way
|
||
that depends on the text’s location—</span><span style="font-size: 10pt"><i>context</i></span><span style="font-size: 10pt">—as well as its content.
|
||
This context, based on the directory of the file containing the text,
|
||
is a central component of Acme’s style of interaction.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme has no single notion of ‘current directory’.
|
||
Instead, every command, file name,
|
||
action, and so on is interpreted or executed in the directory named by the
|
||
tag of the window containing the command. For example, the string
|
||
</span><span style="font-size: 10pt"><tt>mammals</tt></span><span style="font-size: 10pt">
|
||
in a window labeled
|
||
</span><span style="font-size: 10pt"><tt>/lib/</tt></span><span style="font-size: 10pt">
|
||
or
|
||
</span><span style="font-size: 10pt"><tt>/lib/insects</tt></span><span style="font-size: 10pt">
|
||
will be interpreted as the file name
|
||
</span><span style="font-size: 10pt"><tt>/lib/mammals</tt></span><span style="font-size: 10pt">
|
||
if such a file exists.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Throughout Acme, the middle mouse button is used to execute commands
|
||
and the right mouse button is used to locate and select files and text.
|
||
Even when there are no true files on which to operate—for example
|
||
when editing mail messages—Acme and its applications use
|
||
consistent extensions of these basic functions.
|
||
This idea is as vital to Acme as icons are to the Macintosh.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">The middle button executes commands: text swept with the button
|
||
pressed is underlined; when the button is released, the underline is
|
||
removed and the indicated text is executed.
|
||
A modest number of commands are recognized as built-ins: words like
|
||
</span><span style="font-size: 10pt"><tt>Cut</tt></span><span style="font-size: 10pt">,
|
||
</span><span style="font-size: 10pt"><tt>Paste</tt></span><span style="font-size: 10pt">,
|
||
and
|
||
</span><span style="font-size: 10pt"><tt>New</tt></span><span style="font-size: 10pt">
|
||
name
|
||
functions performed directly by Acme.
|
||
These words often appear in tags to make them always available,
|
||
but the tags are not menus: any text anywhere in Acme may be a command.
|
||
For example, in the tag or body of any window one may type
|
||
</span><span style="font-size: 10pt"><tt>Cut</tt></span><span style="font-size: 10pt">,
|
||
select it with the left button, use the middle button to execute it,
|
||
and watch it disappear again.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">If the middle button indicates a command that is not recognized as a built-in,
|
||
it is executed in the directory
|
||
named by the tag of the window holding the text.
|
||
Also, the file to be executed is searched for first in that directory.
|
||
Standard input is connected to
|
||
</span><span style="font-size: 10pt"><tt>/dev/null</tt></span><span style="font-size: 10pt">,
|
||
but standard and error outputs are connected to an Acme window,
|
||
created if needed, called
|
||
</span><span style="font-size: 10pt"><i>dir</i></span><span style="font-size: 10pt"><tt>/+Errors</tt></span><span style="font-size: 10pt"> where
|
||
</span><span style="font-size: 10pt"><i>dir</i></span><span style="font-size: 10pt">
|
||
is the directory of the window.
|
||
(Programs that need interactive input use a different interface, described below.)
|
||
A typical use of this is to type
|
||
</span><span style="font-size: 10pt"><tt>mk</tt></span><span style="font-size: 10pt">
|
||
(Plan 9’s
|
||
</span><span style="font-size: 10pt"><tt>make</tt></span><span style="font-size: 10pt">)
|
||
in the scratch area in the tag of a C source window, say
|
||
</span><span style="font-size: 10pt"><tt>/sys/src/cmd/sam/regexp.c</tt></span><span style="font-size: 10pt">,
|
||
and execute it.
|
||
Output, including compiler errors, appears in the window labeled
|
||
</span><span style="font-size: 10pt"><tt>/sys/src/cmd/sam/+Errors</tt></span><span style="font-size: 10pt">,
|
||
so file names in the output are associated with the windows and directory
|
||
holding the source.
|
||
The
|
||
</span><span style="font-size: 10pt"><tt>mk</tt></span><span style="font-size: 10pt">
|
||
command remains in the tag, serving as a sort of menu item for the associated
|
||
window.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Like the middle button, the right button is used to indicate text by sweeping it out.
|
||
The indicated text is not a command, however, but the argument of a generalized
|
||
search operator.
|
||
If the text, perhaps after appending it to the directory of the window containing it,
|
||
is the name of an existing file, Acme creates a new window to hold the file
|
||
and reads it in. It then moves the mouse cursor to that window. If the file is
|
||
already loaded into Acme, the mouse motion happens but no new window is made.
|
||
For example, indicating the string
|
||
</span><span style="font-size: 10pt"><tt>sam.h</tt></span><span style="font-size: 10pt">
|
||
in
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>#include "sam.h"</tt></span></p>
|
||
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
|
||
<p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">in a window on the file
|
||
</span><span style="font-size: 10pt"><tt>/sys/src/cmd/sam/regexp.c</tt></span><span style="font-size: 10pt">
|
||
will open the file
|
||
</span><span style="font-size: 10pt"><tt>/sys/src/cmd/sam/sam.h</tt></span><span style="font-size: 10pt">.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">If the file name is followed immediately by a colon and a legal address in
|
||
Sam notation (for example a line number or a regular expression delimited in
|
||
slashes or a comma-separated compound of such addresses), Acme highlights
|
||
the target of that address in the file and places the mouse there. One may jump to
|
||
line 27 of
|
||
</span><span style="font-size: 10pt"><tt>dat.h</tt></span><span style="font-size: 10pt">
|
||
by indicating with the right button the text
|
||
</span><span style="font-size: 10pt"><tt>dat.h:27</tt></span><span style="font-size: 10pt">.
|
||
If the file is not already open, Acme loads it.
|
||
If the file name is null, for example if the indicated string is
|
||
</span><span style="font-size: 10pt"><tt>:/^main/</tt></span><span style="font-size: 10pt">,
|
||
the file is assumed to be that of the window containing the string.
|
||
Such strings, when typed and evaluated in the tag of a window, amount to
|
||
context searches.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">If the indicated text is not the name of an existing file, it is taken to be literal
|
||
text and is searched for in the body of the window containing the text, highlighting
|
||
the result as if it were the result of a context search.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">For the rare occasion when a file name
|
||
</span><span style="font-size: 10pt"><i>is</i></span><span style="font-size: 10pt">
|
||
just text to search for, it can be selected with the left button and used as the
|
||
argument to a built-in
|
||
</span><span style="font-size: 10pt"><tt>Look</tt></span><span style="font-size: 10pt">
|
||
command that always searches for literal text.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt"><b>Nuances and heuristics
|
||
</b></span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">A user interface should not only provide the necessary functions, it should also
|
||
</span><span style="font-size: 10pt"><i>feel</i></span><span style="font-size: 10pt">
|
||
right.
|
||
In fact, it should almost not be felt at all; when one notices a
|
||
user interface, one is distracted from the job at hand [Pike88].
|
||
To approach this invisibility, some of Acme’s properties and features
|
||
are there just to make the others easy to use.
|
||
Many are based on a fundamental principle of good design:
|
||
let the machine do the work.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme tries to avoid needless clicking and typing.
|
||
There is no ‘click-to-type’, eliminating a button click.
|
||
There are no pop-up or pull-down menus, eliminating the mouse action needed to
|
||
make a menu appear.
|
||
The overall design is intended to make text on the screen useful without
|
||
copying or retyping; the ways in which this happens involve
|
||
the combination of many aspects of the interface.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme tiles its windows and places them automatically
|
||
to avoid asking the user to place and arrange them.
|
||
For this policy to succeed, the automatic placement must behave well enough
|
||
that the user is usually content with the location of a new window.
|
||
The system will never get it right all the time, but in practice most
|
||
windows are used at least for a while where Acme first places them.
|
||
There have been several complete rewrites of the
|
||
heuristics for placing a new window,
|
||
and with each rewrite the system became
|
||
noticeably more comfortable. The rules are as follows, although
|
||
they are still subject to improvement.
|
||
The window appears in the ‘active’ column, that most recently used for typing or
|
||
selecting.
|
||
Executing and searching do not affect the choice of active column,
|
||
so windows of commands and such do not draw new windows towards them,
|
||
but rather let them form near the targets of their actions.
|
||
Output (error) windows always appear towards the right, away from
|
||
edited text, which is typically kept towards the left.
|
||
Within the column, several competing desires are balanced to decide where
|
||
and how large the window should be:
|
||
large blank spaces should be consumed;
|
||
existing text should remain visible;
|
||
existing large windows should be divided before small ones;
|
||
and the window should appear near the one containing the action that caused
|
||
its creation.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme binds some actions to chords of mouse buttons.
|
||
These include
|
||
</span><span style="font-size: 10pt"><tt>Cut</tt></span><span style="font-size: 10pt">
|
||
and
|
||
</span><span style="font-size: 10pt"><tt>Paste</tt></span><span style="font-size: 10pt">
|
||
so these common operations can be done without
|
||
moving the mouse.
|
||
Another is a way to apply a command in one window to text (often a file name)
|
||
in another, avoiding the actions needed to assemble the command textually.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Another way Acme avoids the need to move the mouse is instead to move the cursor
|
||
to where it is likely to be used next. When a new window is made, Acme
|
||
moves the cursor to the new window; in fact, to the selected text in that window.
|
||
When the user deletes a newly made window, the cursor is
|
||
returned to the point it was before the window was made,
|
||
reducing the irritation of windows that pop up to report annoying errors.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">When a window is moved, Acme moves the cursor to the layout box in
|
||
its new place, to permit further adjustment without moving the mouse.
|
||
For example, when a click of the left mouse button on the layout box grows
|
||
the window, the cursor moves to the new location of the box so repeated clicks,
|
||
without moving the mouse, continue to grow it.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Another form of assistance the system can offer is to supply precision in
|
||
pointing the mouse. The best-known form of this is ‘double-clicking’ to
|
||
select a word rather than carefully sweeping out the entire word.
|
||
Acme provides this feature, using context to decide whether to select
|
||
a word, line, quoted string, parenthesized expression, and so on.
|
||
But Acme takes the idea much further by applying it to execution
|
||
and searching.
|
||
A
|
||
</span><span style="font-size: 10pt"><i>single</i></span><span style="font-size: 10pt">
|
||
click, that is, a null selection, with either the middle or right buttons,
|
||
is expanded automatically to indicate the appropriate text containing
|
||
the click. What is appropriate depends on the context.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">For example, to execute a single-word command
|
||
such as
|
||
</span><span style="font-size: 10pt"><tt>Cut</tt></span><span style="font-size: 10pt">,
|
||
it is not necessary to sweep the entire word; just clicking the button once with
|
||
the mouse pointing at the word is sufficient. ‘Word’
|
||
means the largest string of likely file name characters surrounding the location
|
||
of the click: click on a file name, run that program.
|
||
On the right button, the rules are more complicated because
|
||
the target of the click might be a file name, file name with address,
|
||
or just plain text. Acme examines the text near the click to find
|
||
a likely file name;
|
||
if it finds one, it checks that it names an existing file (in the directory named in the tag, if the name is relative)
|
||
and if so, takes that as the result, after extending it with any address
|
||
that may be present. If there is no file with that name, Acme
|
||
just takes the largest alphanumeric string under the click.
|
||
The effect is a natural overloading of the button to refer to plain text as
|
||
well as file names.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">First, though, if the click occurs over the left-button-selected text in the window,
|
||
that text is taken to be what is selected.
|
||
This makes it easy to skip through the occurrences of a string in a file: just click
|
||
the right button
|
||
on some occurrence of the text in the window (perhaps after typing it in the tag)
|
||
and click once for each subsequent occurrence. It isn’t even necessary to move
|
||
the mouse between clicks; Acme does that.
|
||
To turn a complicated command into a sort of menu item, select it:
|
||
thereafter, clicking the middle button on it will execute the full command.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">As an extra feature, Acme recognizes file names in angle brackets
|
||
</span><span style="font-size: 10pt"><tt><></tt></span><span style="font-size: 10pt">
|
||
as names of files in standard directories of include files,
|
||
making it possible for instance to look at
|
||
</span><span style="font-size: 10pt"><tt><stdio.h></tt></span><span style="font-size: 10pt">
|
||
with a single click.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Here’s an example to demonstrate how the actions and defaults work together.
|
||
Assume
|
||
</span><span style="font-size: 10pt"><tt>/sys/src/cmd/sam/regexp.c</tt></span><span style="font-size: 10pt">
|
||
is
|
||
open and has been edited. We write it (execute
|
||
</span><span style="font-size: 10pt"><tt>Put</tt></span><span style="font-size: 10pt">
|
||
in the tag; once the file is written, Acme removes the word from the tag)
|
||
and type
|
||
</span><span style="font-size: 10pt"><tt>mk</tt></span><span style="font-size: 10pt">
|
||
in the tag. We execute
|
||
</span><span style="font-size: 10pt"><tt>mk</tt></span><span style="font-size: 10pt">
|
||
and get some errors, which appear in a new window labeled
|
||
</span><span style="font-size: 10pt"><tt>/sys/src/cmd/sam/+Errors</tt></span><span style="font-size: 10pt">.
|
||
The cursor moves automatically to that window.
|
||
Say the error is
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>main.c:112: incompatible types on assignment to ‘pattern’</tt></span></p>
|
||
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
|
||
<p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">We move the mouse slightly and click the right button
|
||
at the left of the error message; Acme
|
||
makes a new window, reads
|
||
</span><span style="font-size: 10pt"><tt>/sys/src/cmd/main.c</tt></span><span style="font-size: 10pt">
|
||
into it, selects line 112
|
||
and places the mouse there, right on the offending line.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt"><b>Coupling to existing programs
|
||
</b></span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme’s syntax for file names and addresses makes it easy for other programs
|
||
to connect automatically to Acme’s capabilities. For example, the output of
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>grep -n variable *.[ch]</tt></span></p>
|
||
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
|
||
<p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">can be used to help Acme step through the occurrences of a variable in a program;
|
||
every line of output is potentially a command to open a file.
|
||
The file names need not be absolute, either: the output
|
||
appears in a window labeled with the directory in which
|
||
</span><span style="font-size: 10pt"><tt>grep</tt></span><span style="font-size: 10pt">
|
||
was run, from which Acme can derive the full path names.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">When necessary, we have changed the output of some programs,
|
||
such as compiler error messages, to match
|
||
Acme’s syntax.
|
||
Some might argue that it shouldn’t be necessary to change old programs,
|
||
but sometimes programs need to be updated when systems change,
|
||
and consistent output benefits people as well as programs.
|
||
A historical example is the retrofitting of standard error output to the
|
||
early Unix programs when pipes were invented.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Another change was to record full path names in
|
||
the symbol table of executables, so line numbers reported by the debugger
|
||
are absolute names that may be used directly by Acme; it’s not necessary
|
||
to run the debugger in the source directory. (This aids debugging
|
||
even without Acme.)
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">A related change was to add lines of the form
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>#pragma src "/sys/src/libregexp"</tt></span></p>
|
||
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
|
||
<p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">to header files; coupled with Acme’s ability to locate a header file,
|
||
this provides a fast, keyboardless way to get the source associated with a library.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Finally, Acme directs the standard output of programs it runs to
|
||
windows labeled by the directory in which the program is run.
|
||
Acme’s splitting of the
|
||
output into directory-labeled windows is a small feature that has a major effect:
|
||
local file names printed by programs can be interpreted directly by Acme.
|
||
By indirectly coupling the output of programs to the input,
|
||
it also simplifies the management of software that occupies multiple
|
||
directories.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt"><b>Coupling to new programs
|
||
</b></span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Like many Plan 9 programs,
|
||
Acme offers a programmable interface to
|
||
other programs by acting as a file server.
|
||
The best example of such a file server is the window system
|
||
</span><span style="font-size: 10pt"><tt>8½</tt></span><span style="font-size: 10pt">
|
||
[Pike91],
|
||
which exports files with names such as
|
||
</span><span style="font-size: 10pt"><tt>screen</tt></span><span style="font-size: 10pt">,
|
||
</span><span style="font-size: 10pt"><tt>cons</tt></span><span style="font-size: 10pt">,
|
||
and
|
||
</span><span style="font-size: 10pt"><tt>mouse</tt></span><span style="font-size: 10pt">
|
||
through which applications may access the I/O capabilities of the windows.
|
||
</span><span style="font-size: 10pt"><tt>8½</tt></span><span style="font-size: 10pt">
|
||
provides a
|
||
</span><span style="font-size: 10pt"><i>distinct</i></span><span style="font-size: 10pt">
|
||
set of files for each window and builds a private file name space
|
||
for the clients running ‘in’ each window;
|
||
clients in separate windows see distinct files with the same names
|
||
(for example
|
||
</span><span style="font-size: 10pt"><tt>/dev/mouse</tt></span><span style="font-size: 10pt">).
|
||
Acme, like the process file system [PPTTW93], instead associates each
|
||
window with a directory of files; the files of each window are visible
|
||
to any application.
|
||
This difference reflects a difference in how the systems are used:
|
||
</span><span style="font-size: 10pt"><tt>8½</tt></span><span style="font-size: 10pt">
|
||
tells a client what keyboard and mouse activity has happened in its window;
|
||
Acme tells a client what changes that activity wrought on any window it asks about.
|
||
Putting it another way,
|
||
</span><span style="font-size: 10pt"><tt>8½</tt></span><span style="font-size: 10pt">
|
||
enables the construction of interactive applications;
|
||
Acme provides the interaction for applications.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">The root of
|
||
Acme’s file system is mounted using Plan 9 operations on the directory
|
||
</span><span style="font-size: 10pt"><tt>/mnt/acme</tt></span><span style="font-size: 10pt">.
|
||
In
|
||
that root directory appears a directory for each window, numbered with the window’s identifier,
|
||
analogous to a process identifier, for example
|
||
</span><span style="font-size: 10pt"><tt>/mnt/acme/27</tt></span><span style="font-size: 10pt">.
|
||
The window’s directory
|
||
contains 6 files:
|
||
</span><span style="font-size: 10pt"><tt>/mnt/acme/27/addr</tt></span><span style="font-size: 10pt">,
|
||
</span><span style="font-size: 10pt"><tt>body</tt></span><span style="font-size: 10pt">,
|
||
</span><span style="font-size: 10pt"><tt>ctl</tt></span><span style="font-size: 10pt">,
|
||
</span><span style="font-size: 10pt"><tt>data</tt></span><span style="font-size: 10pt">,
|
||
</span><span style="font-size: 10pt"><tt>event</tt></span><span style="font-size: 10pt">,
|
||
and
|
||
</span><span style="font-size: 10pt"><tt>tag</tt></span><span style="font-size: 10pt">.
|
||
The
|
||
</span><span style="font-size: 10pt"><tt>body</tt></span><span style="font-size: 10pt">
|
||
and
|
||
</span><span style="font-size: 10pt"><tt>tag</tt></span><span style="font-size: 10pt">
|
||
files contain the text of the respective parts of the window; they may be
|
||
read to recover the contents. Data written to these files is appended to the text;
|
||
</span><span style="font-size: 10pt"><tt>seeks</tt></span><span style="font-size: 10pt">
|
||
are ignored.
|
||
The
|
||
</span><span style="font-size: 10pt"><tt>addr</tt></span><span style="font-size: 10pt">
|
||
and
|
||
</span><span style="font-size: 10pt"><tt>data</tt></span><span style="font-size: 10pt">
|
||
files provide random access to the contents of the body.
|
||
The
|
||
</span><span style="font-size: 10pt"><tt>addr</tt></span><span style="font-size: 10pt">
|
||
file is written to set a character position within the body; the
|
||
</span><span style="font-size: 10pt"><tt>data</tt></span><span style="font-size: 10pt">
|
||
file may then be read to recover the contents at that position,
|
||
or written to change them.
|
||
(The tag is assumed
|
||
small and special-purpose enough not to need special treatment.
|
||
Also,
|
||
</span><span style="font-size: 10pt"><tt>addr</tt></span><span style="font-size: 10pt">
|
||
indexes by character position, which is not the same as byte offset
|
||
in Plan 9’s multi-byte character set [Pike93]).
|
||
The format accepted by the
|
||
</span><span style="font-size: 10pt"><tt>addr</tt></span><span style="font-size: 10pt">
|
||
file is exactly the syntax of addresses within the user interface,
|
||
permitting regular expressions, line numbers, and compound addresses
|
||
to be specified. For example, to replace the contents of lines 3 through 7,
|
||
write the text
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>3,7</tt></span></p>
|
||
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
|
||
<p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">to the
|
||
</span><span style="font-size: 10pt"><tt>addr</tt></span><span style="font-size: 10pt">
|
||
file, then write the replacement text to the
|
||
</span><span style="font-size: 10pt"><tt>data</tt></span><span style="font-size: 10pt">
|
||
file. A zero-length write deletes the addressed text; further writes extend the replacement.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">The control file,
|
||
</span><span style="font-size: 10pt"><tt>ctl</tt></span><span style="font-size: 10pt">,
|
||
may be written with commands to effect actions on the window; for example
|
||
the command
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>name /adm/users</tt></span></p>
|
||
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
|
||
<p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">sets the name in the tag of the window to
|
||
</span><span style="font-size: 10pt"><tt>/adm/users</tt></span><span style="font-size: 10pt">.
|
||
Other commands allow deleting the window, writing it to a file, and so on.
|
||
Reading the
|
||
</span><span style="font-size: 10pt"><tt>ctl</tt></span><span style="font-size: 10pt">
|
||
file recovers a fixed-format string containing 5 textual numbers—the window
|
||
identifier, the number of characters in the tag, the number in the body,
|
||
and some status information—followed by the text of the tag, up to a newline.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">The last file,
|
||
</span><span style="font-size: 10pt"><tt>event</tt></span><span style="font-size: 10pt">,
|
||
is the most unusual.
|
||
A program reading a window’s
|
||
</span><span style="font-size: 10pt"><tt>event</tt></span><span style="font-size: 10pt">
|
||
file is notified of all changes to the text of the window, and
|
||
is asked to interpret all middle- and right-button actions.
|
||
The data passed to the program is fixed-format and reports
|
||
the source of the action (keyboard, mouse, external program, etc.),
|
||
its location (what was pointed at or modified), and its nature (change,
|
||
search, execution, etc.).
|
||
This message, for example,
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>MI15 19 0 4 time</tt></span></p>
|
||
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
|
||
<p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">reports that actions of the mouse
|
||
(</span><span style="font-size: 10pt"><tt>M</tt></span><span style="font-size: 10pt">)
|
||
inserted in the body (capital
|
||
</span><span style="font-size: 10pt"><tt>I</tt></span><span style="font-size: 10pt">)
|
||
the 4 characters of
|
||
</span><span style="font-size: 10pt"><tt>time</tt></span><span style="font-size: 10pt">
|
||
at character positions 15 through 19; the zero is a flag word.
|
||
Programs may apply their own interpretations of searching and
|
||
execution, or may simply reflect the events back to Acme,
|
||
by writing them back to the
|
||
</span><span style="font-size: 10pt"><tt>event</tt></span><span style="font-size: 10pt">
|
||
file, to have the default interpretation applied.
|
||
Some examples of these ideas in action are presented below.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Notice that changes to the window are reported
|
||
after the fact; the program is told about them but is not required to act
|
||
on them. Compare this to a more traditional interface in which a program
|
||
is told, for example, that a character has been typed on the keyboard and
|
||
must then display and interpret it.
|
||
Acme’s style stems from the basic model of the system, in which any
|
||
number of agents—the keyboard, mouse, external programs
|
||
writing to
|
||
</span><span style="font-size: 10pt"><tt>data</tt></span><span style="font-size: 10pt">
|
||
or
|
||
</span><span style="font-size: 10pt"><tt>body</tt></span><span style="font-size: 10pt">,
|
||
and so on—may
|
||
change the contents of a window.
|
||
The style is efficient: many programs are content
|
||
to have Acme do most of the work and act only when the editing is completed.
|
||
An example is the Acme mail program, which can ignore the changes
|
||
made to a message being composed
|
||
and just read its body when asked to send it.
|
||
A disadvantage is that some traditional ways of working are impossible.
|
||
For example, there is no way ‘to turn off echo’: characters appear on the
|
||
screen and are read from there; no agent or buffer stands between
|
||
the keyboard and the display.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">There are a couple of other files made available by Acme in its root directory
|
||
rather than in the directory of each window.
|
||
The text file
|
||
</span><span style="font-size: 10pt"><tt>/mnt/acme/index</tt></span><span style="font-size: 10pt">
|
||
holds a list of all window names and numerical identifiers,
|
||
somewhat analogous to the output of the
|
||
</span><span style="font-size: 10pt"><tt>ps</tt></span><span style="font-size: 10pt">
|
||
command for processes.
|
||
The most important, though, is
|
||
</span><span style="font-size: 10pt"><tt>/mnt/acme/new</tt></span><span style="font-size: 10pt">,
|
||
a directory that makes new windows, similar to the
|
||
</span><span style="font-size: 10pt"><tt>clone</tt></span><span style="font-size: 10pt">
|
||
directory in the Plan 9 network devices [Pres93].
|
||
The act of opening any file in
|
||
</span><span style="font-size: 10pt"><tt>new</tt></span><span style="font-size: 10pt">
|
||
creates a new Acme window; thus the shell command
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>grep -n var *.c > /mnt/acme/new/body</tt></span></p>
|
||
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
|
||
<p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">places its output in the body of a fresh window.
|
||
More sophisticated applications may open
|
||
</span><span style="font-size: 10pt"><tt>new/ctl</tt></span><span style="font-size: 10pt">,
|
||
read it to discover the new window’s identifier, and then
|
||
open the window’s other files in the numbered directory.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt"><b>Acme-specific programs
|
||
</b></span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Although Acme is in part an attempt to move beyond typescripts,
|
||
they will probably always have utility.
|
||
The first program written for Acme was therefore one
|
||
to run a shell or other traditional interactive application
|
||
in a window, the Acme analog of
|
||
</span><span style="font-size: 10pt"><tt>xterm</tt></span><span style="font-size: 10pt">.
|
||
This program,
|
||
</span><span style="font-size: 10pt"><tt>win</tt></span><span style="font-size: 10pt">,
|
||
has a simple structure:
|
||
it acts as a two-way intermediary between Acme and the shell,
|
||
cross-connecting the standard input and output of the shell to the
|
||
text of the window.
|
||
The style of interaction is modeled after
|
||
</span><span style="font-size: 10pt"><tt>mux</tt></span><span style="font-size: 10pt">
|
||
[Pike88]: standard output is added to the window at the
|
||
</span><span style="font-size: 10pt"><i>output point;</i></span><span style="font-size: 10pt">
|
||
text typed after the output point
|
||
is made available on standard input when a newline is typed.
|
||
After either of these actions, the output point is advanced.
|
||
This is different from the working of a regular terminal,
|
||
permitting cut-and-paste editing of an input line until the newline is typed.
|
||
Arbitrary editing may be done to any text in the window.
|
||
The implementation of
|
||
</span><span style="font-size: 10pt"><tt>win</tt></span><span style="font-size: 10pt">,
|
||
using the
|
||
</span><span style="font-size: 10pt"><tt>event</tt></span><span style="font-size: 10pt">,
|
||
</span><span style="font-size: 10pt"><tt>addr</tt></span><span style="font-size: 10pt">,
|
||
and
|
||
</span><span style="font-size: 10pt"><tt>data</tt></span><span style="font-size: 10pt">
|
||
files, is straightforward.
|
||
</span><span style="font-size: 10pt"><tt>Win</tt></span><span style="font-size: 10pt">
|
||
needs no code for handling the keyboard and mouse; it just monitors the
|
||
contents of the window. Nonetheless, it allows Acme’s full editing to be
|
||
applied to shell commands.
|
||
The division of labor between
|
||
</span><span style="font-size: 10pt"><tt>win</tt></span><span style="font-size: 10pt">
|
||
and
|
||
</span><span style="font-size: 10pt"><tt>Acme</tt></span><span style="font-size: 10pt">
|
||
contrasted with
|
||
</span><span style="font-size: 10pt"><tt>xterm</tt></span><span style="font-size: 10pt">
|
||
and the X server demonstrates how much work Acme handles automatically.
|
||
</span><span style="font-size: 10pt"><tt>Win</tt></span><span style="font-size: 10pt">
|
||
is implemented by a single source file 560 lines long and has no graphics code.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt"></span><span style="font-size: 10pt"><tt>Win</tt></span><span style="font-size: 10pt">
|
||
uses the middle and right buttons to connect itself in a consistent way
|
||
with the rest of Acme.
|
||
The middle button still executes commands, but in a style more suited
|
||
to typescripts. Text selected with the middle button is treated as if
|
||
it had been typed after the output point, much as a similar feature in
|
||
</span><span style="font-size: 10pt"><tt>xterm</tt></span><span style="font-size: 10pt">
|
||
or
|
||
</span><span style="font-size: 10pt"><tt>8½</tt></span><span style="font-size: 10pt">,
|
||
and therefore causes it to be ‘executed’ by the application running in the window.
|
||
Right button actions are reflected back to Acme but refer to the appropriate
|
||
files because
|
||
</span><span style="font-size: 10pt"><tt>win</tt></span><span style="font-size: 10pt">
|
||
places the name of the current directory in the tag of the window.
|
||
If the shell is running, a simple shell function replacing the
|
||
</span><span style="font-size: 10pt"><tt>cd</tt></span><span style="font-size: 10pt">
|
||
command can maintain the tag as the shell navigates the file system.
|
||
This means, for example, that a right button click on a file mentioned in an
|
||
</span><span style="font-size: 10pt"><tt>ls</tt></span><span style="font-size: 10pt">
|
||
listing opens the file within Acme.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Another Acme-specific program is a mail reader that begins by presenting,
|
||
in a window, a listing of the messages in the user’s mailbox, one per line.
|
||
Here the middle and right button actions are modified to refer to
|
||
mail commands
|
||
and messages, but the change feels natural.
|
||
Clicking the right button on a line creates a new window and displays the
|
||
message there, or, if it’s already displayed, moves the mouse to that window.
|
||
The metaphor is that the mailbox is a directory whose constituent files are messages.
|
||
The mail program also places some relevant commands in the tag lines of
|
||
the windows; for example, executing the word
|
||
</span><span style="font-size: 10pt"><tt>Reply</tt></span><span style="font-size: 10pt">
|
||
in a message’s tag creates a new window
|
||
in which to compose a message to the sender of the original;
|
||
</span><span style="font-size: 10pt"><tt>Post</tt></span><span style="font-size: 10pt">
|
||
then dispatches it.
|
||
In such windows, the addressee is just a list of names
|
||
on the first line of the body, which may be edited to add or change recipients.
|
||
The program also monitors the mailbox, updating the ‘directory’ as new messages
|
||
arrive.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">The mail program is as simple as it sounds; all the work of interaction,
|
||
editing, and management of the display is done by Acme.
|
||
The only
|
||
difficult sections of the 1200
|
||
lines of code concern honoring the external protocols for managing
|
||
the mailbox and connecting to
|
||
</span><span style="font-size: 10pt"><tt>sendmail</tt></span><span style="font-size: 10pt">.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">One of the things Acme does not provide directly is a facility like
|
||
Sam’s command language to enable actions such as global substitution;
|
||
within Acme, all editing is done manually.
|
||
It is easy, though, to write external programs for such tasks.
|
||
In this, Acme comes closer to the original intent of Oberon:
|
||
a directory,
|
||
</span><span style="font-size: 10pt"><tt>/acme/edit</tt></span><span style="font-size: 10pt">,
|
||
contains a set of tools for repetitive editing and a template
|
||
or ‘guide’ file that gives examples
|
||
of its use.
|
||
Acme’s editing guide,
|
||
</span><span style="font-size: 10pt"><tt>/acme/edit/guide</tt></span><span style="font-size: 10pt">,
|
||
looks like this:
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>e file | x ’/regexp/’ | c ’replacement’</tt></span></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>e file:’0,$’ | x ’/.*word.*\n/’ | p -n</tt></span></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>e file | pipe command args ...</tt></span></p>
|
||
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
|
||
<p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">The syntax is reminiscent of Sam’s command language, but here the individual
|
||
one-letter commands are all stand-alone programs connected by pipes.
|
||
Passed along the pipes are addresses, analogous to structural expressions
|
||
in Sam terminology.
|
||
The
|
||
</span><span style="font-size: 10pt"><tt>e</tt></span><span style="font-size: 10pt">
|
||
command, unlike that of Sam, starts the process by generating the address
|
||
(default dot, the highlighted selection) in the named files.
|
||
The other commands are as in Sam:
|
||
</span><span style="font-size: 10pt"><tt>p</tt></span><span style="font-size: 10pt">
|
||
prints the addressed text on standard output (the
|
||
</span><span style="font-size: 10pt"><tt>-n</tt></span><span style="font-size: 10pt">
|
||
option is analogous to that of
|
||
</span><span style="font-size: 10pt"><tt>grep</tt></span><span style="font-size: 10pt">,
|
||
useful in combination with the right mouse button);
|
||
</span><span style="font-size: 10pt"><tt>x</tt></span><span style="font-size: 10pt">
|
||
matches a regular expression to the addressed (incoming) text,
|
||
subdividing the text;
|
||
</span><span style="font-size: 10pt"><tt>c</tt></span><span style="font-size: 10pt">
|
||
replaces the text; and so on. Thus, global substitution throughout a file,
|
||
which would be expressed in Sam as
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>0,$ x/regexp/ c/replacement/</tt></span></p>
|
||
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
|
||
<p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">in Acme’s editor becomes
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>e ’file:0,$’ | x ’/regexp/’ | c ’replacement’</tt></span></p>
|
||
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
|
||
<p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">To use the Acme editing commands, open
|
||
</span><span style="font-size: 10pt"><tt>/acme/edit/guide</tt></span><span style="font-size: 10pt">,
|
||
use the mouse and keyboard to edit one of the commands to the right form,
|
||
and execute it with the middle button.
|
||
Acme’s context rules find the appropriate binaries in
|
||
</span><span style="font-size: 10pt"><tt>/acme/edit</tt></span><span style="font-size: 10pt">
|
||
rather than
|
||
</span><span style="font-size: 10pt"><tt>/bin</tt></span><span style="font-size: 10pt">;
|
||
the effect is to turn
|
||
</span><span style="font-size: 10pt"><tt>/acme/edit</tt></span><span style="font-size: 10pt">
|
||
into a toolbox containing tools and instructions (the guide file) for their use.
|
||
In fact, the source for these tools is also there, in the directory
|
||
</span><span style="font-size: 10pt"><tt>/acme/edit/src</tt></span><span style="font-size: 10pt">.
|
||
This setup allows some control of the file name space for binary programs;
|
||
not only does it group related programs, it permits the use of common
|
||
names for uncommon jobs. For example, the single-letter names would
|
||
be unwise in a directory in everyone’s search path; here they are only
|
||
visible when running editing commands.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">In Oberon,
|
||
such a collection would be called a
|
||
</span><span style="font-size: 10pt"><i>tool</i></span><span style="font-size: 10pt">
|
||
and would consist
|
||
of a set of entry points in a module and a menu-like piece of text containing
|
||
representative commands that may be edited to suit and executed.
|
||
There is, in fact, a tool called
|
||
</span><span style="font-size: 10pt"><tt>Edit</tt></span><span style="font-size: 10pt">
|
||
in Oberon.
|
||
To provide related functionality,
|
||
Acme exploits the directory and file structure of the underlying
|
||
system, rather than the module structure of the language;
|
||
this fits well with Plan 9’s
|
||
file-oriented philosophy.
|
||
Such tools are central to the working of Oberon but they are
|
||
less used in Acme, at least so far.
|
||
The main reason is probably that Acme’s program interface permits
|
||
an external program to remain executing in the background, providing
|
||
its own commands as needed (for example, the
|
||
</span><span style="font-size: 10pt"><tt>Reply</tt></span><span style="font-size: 10pt">
|
||
command in the mail program); Oberon uses tools to
|
||
implement such services because its must invoke
|
||
a fresh program for each command.
|
||
Also,
|
||
Acme’s better integration allows more
|
||
basic functions to be handled internally; the right mouse button
|
||
covers a lot of the basic utility of the editing tools in Oberon.
|
||
Nonetheless, as more applications are written for Acme,
|
||
many are sure to take this Oberon tool-like form.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt"><b>Comparison with other systems
|
||
</b></span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme’s immediate ancestor is Help [Pike92], an experimental system written
|
||
a few years ago as a first try at exploring some of Oberon’s ideas
|
||
in an existing operating system.
|
||
Besides much better engineering, Acme’s advances over Help
|
||
include the actions of the right button (Help had nothing comparable),
|
||
the ability to connect long-running programs to the user interface
|
||
(Help had no analog of the
|
||
</span><span style="font-size: 10pt"><tt>event</tt></span><span style="font-size: 10pt">
|
||
file),
|
||
and the small but important change to split command output into
|
||
windows labeled with the directory in which the commands run.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Most of Acme’s style, however, derives from the user interface and window
|
||
system of Oberon [Wirt89, Reis91].
|
||
Oberon includes a programming language and operating system,
|
||
which Acme instead borrows from an existing system, Plan 9.
|
||
When I first saw Oberon, in 1988, I was struck by the
|
||
simplicity of its user interface, particularly its lack of menus
|
||
and its elegant use of multiple mouse buttons.
|
||
The system seemed restrictive, though—single process,
|
||
single language, no networking, event-driven programming—and
|
||
failed to follow through on some of its own ideas.
|
||
For example, the middle mouse button had to be pointed accurately and
|
||
the right button was essentially unused.
|
||
Acme does follow through:
|
||
to the basic idea planted by Oberon, it adds
|
||
the ability to run on different operating systems and hardware,
|
||
connection to existing applications including
|
||
interactive ones such as shells and debuggers,
|
||
support for multiple processes,
|
||
the right mouse button’s features,
|
||
the default actions and context-dependent properties
|
||
of execution and searching,
|
||
and a host of little touches such as moving the mouse cursor that make the system
|
||
more pleasant.
|
||
At the moment, though, Oberon does have one distinct advantage: it incorporates
|
||
graphical programs well into its model, an issue Acme has not yet faced.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme shares with the Macintosh a desire to use the mouse well and it is
|
||
worth comparing the results.
|
||
The mouse on the Macintosh has a single button, so menus are essential
|
||
and the mouse must frequently move a long way
|
||
to reach the appropriate function.
|
||
An indication that this style has trouble is that applications provide
|
||
keyboard sequences to invoke menu selections and users often prefer them.
|
||
A deeper comparison is that the Macintosh uses pictures where Acme uses text.
|
||
In contrast to pictures, text can be edited quickly, created on demand,
|
||
and fine-tuned to the job at hand; consider adding an option to a command.
|
||
It is also self-referential; Acme doesn’t need menus because any text can be
|
||
in effect a menu item.
|
||
The result is that, although a Macintosh screen is certainly prettier and probably
|
||
more attractive, especially to beginners, an Acme screen is more dynamic
|
||
and expressive, at least for programmers and experienced users.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">For its role in the overall system,
|
||
Acme most resembles EMACS [Stal93].
|
||
It is tricky to compare Acme to EMACS, though, because there are
|
||
many versions of EMACS and, since it is fully programmable, EMACS
|
||
can in principle do anything Acme does.
|
||
Also, Acme is much younger and therefore has not
|
||
had the time to acquire as many features.
|
||
The issue therefore is less what the systems can be programmed to do than
|
||
how they are used.
|
||
The EMACS versions that come closest to Acme’s style are those that
|
||
have been extended to provide a programming environment, usually
|
||
for a language such as LISP [Alle92, Lucid92].
|
||
For richness of the existing interface, these EMACS versions are certainly superior to Acme.
|
||
On the other hand, Acme’s interface works equally well already for a variety
|
||
of languages; for example, one of its most enthusiastic users works almost
|
||
exclusively in Standard ML, a language nothing like C.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Where Acme excels is in the smoothness of its interface.
|
||
Until recently, EMACS did not support the mouse especially well,
|
||
and even with the latest version providing features such as ‘extents’
|
||
that can be programmed to behave much like Acme commands,
|
||
many users don’t bother to upgrade.
|
||
Moreover, in the versions that provide extents,
|
||
most EMACS packages don’t take advantage of them.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">The most important distinction is just that
|
||
EMACS is fundamentally keyboard-based, while
|
||
Acme is mouse-based.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">People who try Acme find it hard to go back to their previous environment.
|
||
Acme automates so much that to return to a traditional interface
|
||
is to draw attention to the extra work it requires.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt"><b>Concurrency in the implementation
|
||
</b></span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme is about 8,000 lines of code in Alef, a concurrent object-oriented language syntactically similar to C [Alef].
|
||
Acme’s structure is a set of communicating
|
||
processes in a single address space.
|
||
One subset of the processes drives the display and user interface,
|
||
maintaining the windows; other processes forward mouse and keyboard
|
||
activity and implement the file server interface for external programs.
|
||
The language and design worked out well;
|
||
as explained elsewhere [Pike89, Gans93, Reppy93],
|
||
user interfaces built with concurrent systems
|
||
can avoid the clumsy
|
||
top-level event loop typical of traditional interactive systems.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">An example of the benefits of the multi-process style
|
||
is the management of the state of open
|
||
files held by clients of the file system interface.
|
||
The problem is that some I/O requests,
|
||
such as reading the
|
||
</span><span style="font-size: 10pt"><tt>event</tt></span><span style="font-size: 10pt">
|
||
file, may block if no data is available, and the server must
|
||
maintain the state of (possibly many) requests until data appears.
|
||
For example,
|
||
in
|
||
</span><span style="font-size: 10pt"><tt>8½</tt></span><span style="font-size: 10pt">,
|
||
a single-process window system written in C, pending requests were queued in
|
||
a data structure associated with each window.
|
||
After activity in the window that might complete pending I/O,
|
||
the data structure was scanned for requests that could now finish.
|
||
This structure did not fit well with the rest of the program and, worse,
|
||
required meticulous effort
|
||
to guarantee correct behavior under all conditions
|
||
(consider raw mode, reads of partial lines, deleting a window,
|
||
multibyte characters, etc.).
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme instead creates a new dedicated process
|
||
for each I/O request.
|
||
This process coordinates with the rest of the system
|
||
using Alef’s synchronous communication;
|
||
its state implicitly encodes the state of
|
||
the I/O request and obviates the need for queuing.
|
||
The passage of the request through Acme proceeds as follows.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme contains a file server process, F, that executes a
|
||
</span><span style="font-size: 10pt"><tt>read</tt></span><span style="font-size: 10pt">
|
||
system call to receive a Plan 9 file protocol (9P) message from the client [AT&T92].
|
||
The client blocks until Acme answers the request.
|
||
F communicates with an allocation process, M,
|
||
to acquire an object of type
|
||
</span><span style="font-size: 10pt"><tt>Xfid</tt></span><span style="font-size: 10pt">
|
||
(‘executing fid’; fid is a 9P term)
|
||
to hold the request.
|
||
M sits in a loop (reproduced in Figure 2) waiting for either a request for
|
||
a new
|
||
</span><span style="font-size: 10pt"><tt>Xfid</tt></span><span style="font-size: 10pt">
|
||
or notification that an existing one has finished its task.
|
||
When an
|
||
</span><span style="font-size: 10pt"><tt>Xfid</tt></span><span style="font-size: 10pt">
|
||
is created, an associated process, X,
|
||
is also made.
|
||
M queues idle
|
||
</span><span style="font-size: 10pt"><tt>Xfids</tt></span><span style="font-size: 10pt">,
|
||
allocating new ones only when the list is empty.
|
||
Thus, there is always a pool of
|
||
</span><span style="font-size: 10pt"><tt>Xfids</tt></span><span style="font-size: 10pt">,
|
||
some executing, some idle.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">The
|
||
</span><span style="font-size: 10pt"><tt>Xfid</tt></span><span style="font-size: 10pt">
|
||
object contains a channel,
|
||
</span><span style="font-size: 10pt"><tt>Xfid.c</tt></span><span style="font-size: 10pt">,
|
||
for communication with its process;
|
||
the unpacked message; and some associated functions,
|
||
mostly corresponding to 9P messages such as
|
||
</span><span style="font-size: 10pt"><tt>Xfid.write</tt></span><span style="font-size: 10pt">
|
||
to handle a 9P write request.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">The file server process F parses the message to see its nature—open,
|
||
close, read, write, etc. Many messages, such as directory
|
||
lookups, can be handled immediately; these are responded to directly
|
||
and efficiently
|
||
by F without invoking the
|
||
</span><span style="font-size: 10pt"><tt>Xfid</tt></span><span style="font-size: 10pt">,
|
||
which is therefore maintained until the next message.
|
||
When a message, such as a write to the display, requires the attention
|
||
of the main display process and interlocked access to its data structures,
|
||
F enables X
|
||
by sending a function pointer on
|
||
</span><span style="font-size: 10pt"><tt>Xfid.c</tt></span><span style="font-size: 10pt">.
|
||
For example, if the message is a write, F executes
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>x->c <-= Xfid.write;</tt></span></p>
|
||
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
|
||
<p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">which sends
|
||
the address of
|
||
</span><span style="font-size: 10pt"><tt>Xfid.write</tt></span><span style="font-size: 10pt">
|
||
on
|
||
</span><span style="font-size: 10pt"><tt>Xfid.c</tt></span><span style="font-size: 10pt">,
|
||
waking up X.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">The
|
||
</span><span style="font-size: 10pt"><tt>Xfid</tt></span><span style="font-size: 10pt">
|
||
process, X, executes a simple loop:
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>void</tt></span></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>Xfid.ctl(Xfid *x)</tt></span></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>{</tt></span></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt> for(;;){</tt></span></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt> (*<-x->c)(x); /* receive and execute message */</tt></span></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt> bflush(); /* synchronize bitmap display */</tt></span></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt> cxfidfree <-= x; /* return to free list */</tt></span></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt> }</tt></span></p>
|
||
<p style="line-height: 1.1em; margin-left: 1.28in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 9pt"><tt>}</tt></span></p>
|
||
<p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
|
||
<p style="margin-top: 0; margin-bottom: 0.08in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Thus X
|
||
will wake up with the address of a function to call (here
|
||
</span><span style="font-size: 10pt"><tt>Xfid.write</tt></span><span style="font-size: 10pt">)
|
||
and execute it; once that completes, it returns itself to the pool of
|
||
free processes by sending its address back to the allocator.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Although this sequence may seem complicated, it is just a few lines
|
||
of code and is in fact far simpler
|
||
than the management of the I/O queues in
|
||
</span><span style="font-size: 10pt"><tt>8½</tt></span><span style="font-size: 10pt">.
|
||
The hard work of synchronization is done by the Alef run time system.
|
||
Moreover, the code worked the first time, which cannot be said for the code in
|
||
</span><span style="font-size: 10pt"><tt>8½</tt></span><span style="font-size: 10pt">.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt"><b>Undo
|
||
</b></span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme provides a general undo facility like that of Sam, permitting
|
||
textual changes to be unwound arbitrarily.
|
||
The implementation is superior to Sam’s, though,
|
||
with much higher performance and the ability to ‘redo’ changes.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Sam uses
|
||
a multi-pass algorithm that builds
|
||
a transcript of changes to be made simultaneously
|
||
and then executes them atomically.
|
||
This was thought necessary because the elements of a repetitive
|
||
command such as a global substitution should all be applied to the same
|
||
initial file and implemented simultaneously; forming the complete
|
||
transcript before executing any of the changes avoids the
|
||
cumbersome management of addresses in a changing file.
|
||
Acme, however, doesn’t have this problem; global substitution
|
||
is controlled externally and may be made incrementally by exploiting
|
||
an observation: if the changes are sorted in address order and
|
||
executed in reverse, changes will not invalidate the addresses of
|
||
pending changes.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme therefore avoids the initial transcript. Instead, changes are applied
|
||
directly to the file, with an undo transcript recorded in a separate list.
|
||
For example, when text is added to a window, it is added directly and a record
|
||
of what to delete to restore the state is appended to the undo list.
|
||
Each undo action and the file are marked with a sequence number;
|
||
actions with the same sequence number are considered a unit
|
||
to be undone together.
|
||
The invariant state of the structure
|
||
is that the last action in the undo list applies to the current state of the file,
|
||
even if that action is one of a related set from, for example, a global substitute.
|
||
(In Sam, a related set of actions needed to be undone simultaneously.)
|
||
To undo an action, pop the last item on the undo list, apply it to the file,
|
||
revert it, and append it to a second, redo list.
|
||
To redo an action, do the identical operation with the lists interchanged.
|
||
The expensive operations occur
|
||
only when actually undoing; in normal editing the overhead is minor.
|
||
For example, Acme reads files about seven times faster than Sam, partly
|
||
because of this improvement and partly because of a cleaner implementation.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme uses a temporary file to hold the text, keeping in memory only the
|
||
visible portion, and therefore can edit large files comfortably
|
||
even on small-memory machines such as laptops.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt"><b>Future
|
||
</b></span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme is still under development.
|
||
Some things are simply missing.
|
||
For example, Acme should support non-textual graphics, but this is being
|
||
deferred until it can be done using a new graphics model being developed
|
||
for Plan 9. Also, it is undecided how Acme’s style of interaction should best be
|
||
extended to graphical applications.
|
||
On a smaller scale, although the system feels smooth and comfortable,
|
||
work continues to tune the heuristics and
|
||
try new ideas for the user interface.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">There need to be more programs that use Acme. Browsers for
|
||
Usenet and AP News articles, the Oxford English Dictionary, and other
|
||
such text sources exist, but more imaginative applications will
|
||
be necessary to prove that Acme’s approach is viable.
|
||
One that has recently been started is an interface to the debugger Acid [Wint94],
|
||
although it is still
|
||
unclear what form it will ultimately take.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme shows that it is possible to make a user interface a stand-alone component
|
||
of an interactive environment. By absorbing more of the interactive
|
||
functionality than a simple window system, Acme off-loads much of the
|
||
computation from its applications, which helps keep them small and
|
||
consistent in their interface. Acme can afford to dedicate
|
||
considerable effort to making that interface as good as possible; the result
|
||
will benefit the entire system.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Acme is complete and useful enough to attract users.
|
||
Its comfortable user interface,
|
||
the ease with which it handles multiple tasks and
|
||
programs in multiple directories,
|
||
and its high level of integration
|
||
make it addictive.
|
||
Perhaps most telling,
|
||
Acme shows that typescripts may not be the most
|
||
productive interface to a time-sharing system.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt"><b>Acknowledgements
|
||
</b></span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.35in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">Howard Trickey, Acme’s first user, suffered buggy versions gracefully and made
|
||
many helpful suggestions. Chris Fraser provided the necessary insight for the Acme editing
|
||
commands.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.17in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt"><b>References
|
||
</b></span></p><p style="margin-top: 0; margin-bottom: 0.05in"></p>
|
||
<p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Alef] P. Winterbottom,
|
||
‘‘Alef Language Reference Manual’’,
|
||
</span><span style="font-size: 10pt"><i>Plan 9 Programmer’s Manual,
|
||
</i></span><span style="font-size: 10pt">AT&T Bell Laboratories,
|
||
Murray Hill, NJ,
|
||
1992;
|
||
revised in this volume.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Alle92]
|
||
</span><span style="font-size: 10pt"><i>Allegro Common Lisp user Guide, Vol 2,
|
||
</i></span><span style="font-size: 10pt">Chapter 14, "The Emacs-Lisp Interface".
|
||
March 1992.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[AT&T92] Plan 9 Programmer’s manual, Murray Hill, New Jersey, 1992.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Far89] Far too many people, XTERM(1), Massachusetts Institute of Technology, 1989.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Gans93] Emden R. Gansner and John H. Reppy, ‘‘A Multi-threaded Higher-order User Interface Toolkit’’, in
|
||
</span><span style="font-size: 10pt"><i>Software Trends, Volume 1,
|
||
User Interface Software,
|
||
</i></span><span style="font-size: 10pt">Bass and Dewan (Eds.),
|
||
John Wiley & Sons 1993,
|
||
pp. 61-80.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Lucid92] Richard Stallman and Lucid, Inc.,
|
||
</span><span style="font-size: 10pt"><i>Lucid GNU EMACS Manual,
|
||
</i></span><span style="font-size: 10pt">March 1992.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Pike87] Rob Pike, ‘‘The Text Editor </span><span style="font-size: 10pt"><tt>sam</tt></span><span style="font-size: 10pt">’’, Softw. - Pract. and Exp., Nov 1987, Vol 17 #11, pp. 813-845; reprinted in this volume.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Pike88] Rob Pike, ‘‘Window Systems Should Be Transparent’’, Comp. Sys., Summer 1988, Vol 1 #3, pp. 279-296.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Pike89] Rob Pike, ‘‘A Concurrent Window System’’, Comp. Sys., Spring 1989, Vol 2 #2, pp. 133-153.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[PPTTW93] Rob Pike, Dave Presotto, Ken Thompson, Howard Trickey, and Phil Winterbottom, ‘‘The Use of Name Spaces in Plan 9’’,
|
||
Op. Sys. Rev., Vol. 27, No. 2, April 1993, pp. 72-76,
|
||
reprinted in this volume.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Pike91] Rob Pike, ‘‘8½, the Plan 9 Window System’’, USENIX Summer Conf. Proc., Nashville, June, 1991, pp. 257-265,
|
||
reprinted in this volume.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Pike92] Rob Pike, ‘‘A Minimalist Global User Interface’’, Graphics Interface ’92 Proc., Vancouver, 1992, pp. 282-293. An earlier version appeared under the same title in USENIX Summer Conf. Proc., Nashville, June, 1991, pp. 267-279.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Pike93] Rob Pike and Ken Thompson, ‘‘Hello World or Καλημέρα κόσμε or
|
||
</span><span style="font-size: 10pt">こんにちは 世界</span><span style="font-size: 10pt">’’, USENIX Winter Conf. Proc., San Diego, 1993, pp. 43-50,
|
||
reprinted in this volume.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Pres93] Dave Presotto and Phil Winterbottom, ‘‘The Organization of Networks in Plan 9’’, Proc. Usenix Winter 1993, pp. 271-287, San Diego, CA,
|
||
reprinted in this volume.
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</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">[Reis91] Martin Reiser, </span><span style="font-size: 10pt"><i>The Oberon System,</i></span><span style="font-size: 10pt"> Addison Wesley, New York, 1991.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Reppy93] John H. Reppy,
|
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‘‘CML: A higher-order concurrent language’’, Proc. SIGPLAN’91 Conf. on Programming, Lang. Design and Impl., June, 1991, pp. 293-305.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Sche86] Robert W. Scheifler and Jim Gettys,
|
||
‘‘The X Window System’’,
|
||
ACM Trans. on Graph., Vol 5 #2, pp. 79-109.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Stal93] Richard Stallman,
|
||
</span><span style="font-size: 10pt"><i>Gnu Emacs Manual, 9th edition, Emacs version 19.19,
|
||
</i></span><span style="font-size: 10pt">MIT.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Swei86] Daniel Sweinhart, Polle Zellweger, Richard Beach, and Robert Hagmann,
|
||
‘‘A Structural View of the Cedar Programming Environment’’,
|
||
ACM Trans. Prog. Lang. and Sys., Vol. 8, No. 4, pp. 419-490, Oct. 1986.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Wint94], Philip Winterbottom, ‘‘Acid: A Debugger based on a Language’’, USENIX Winter Conf. Proc., San Francisco, CA, 1993,
|
||
reprinted in this volume.
|
||
</span></p><p style="line-height: 1.2em; margin-left: 1.00in; text-indent: 0.00in; margin-right: 1.00in; margin-top: 0; margin-bottom: 0; text-align: justify;">
|
||
<span style="font-size: 10pt">[Wirt89] N. Wirth and J. Gutknecht, ‘‘The Oberon System’’, Softw. - Prac. and Exp., Sep 1989, Vol 19 #9, pp 857-894.
|
||
</span></p><p style="margin-top: 0; margin-bottom: 0.50in"></p>
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<p style="margin-top: 0; margin-bottom: 0.17in"></p>
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<p style="line-height: 1.2em; margin-left: 1.50in; text-indent: 0.35in; margin-right: 1.50in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt"></span><span style="font-size: 10pt"><b>Notes</b></span><span style="font-size: 10pt">
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</span></p><p style="margin-top: 0; margin-bottom: 0.17in"></p>
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<p style="margin-top: 0; margin-bottom: 0.17in"></p>
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<p style="line-height: 1.2em; margin-left: 1.50in; text-indent: 0.00in; margin-right: 1.50in; margin-top: 0; margin-bottom: 0; text-align: justify;">
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<span style="font-size: 10pt">Originally appeared in
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</span><span style="font-size: 10pt"><i>Proc. of the Winter 1994 USENIX Conf.,
|
||
</i></span><span style="font-size: 10pt">pp. 223-234,
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||
San Francisco, CA
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</span></p><p style="margin-top: 0; margin-bottom: 0.17in"></p>
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