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diff --git a/manuals/chickadee/Scripts.html b/manuals/chickadee/Scripts.html new file mode 100644 index 0000000..c9939f5 --- /dev/null +++ b/manuals/chickadee/Scripts.html @@ -0,0 +1,209 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 2017 David Thompson davet@gnu.org + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 +or any later version published by the Free Software Foundation; +with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. +A copy of the license is included in the section entitled "GNU +Free Documentation License". + +A copy of the license is also available from the Free Software +Foundation Web site at http://www.gnu.org/licenses/fdl.html. + + +The document was typeset with +http://www.texinfo.org/ (GNU Texinfo). + --> +<!-- Created by GNU Texinfo 6.5, http://www.gnu.org/software/texinfo/ --> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<title>Scripts (The Chickadee Game Toolkit)</title> + +<meta name="description" content="Scripts (The Chickadee Game Toolkit)"> +<meta name="keywords" content="Scripts (The Chickadee Game Toolkit)"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Index.html#Index" rel="index" title="Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Scripting.html#Scripting" rel="up" title="Scripting"> +<link href="Tweening.html#Tweening" rel="next" title="Tweening"> +<link href="Agendas.html#Agendas" rel="prev" title="Agendas"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.indentedblock {margin-right: 0em} +blockquote.smallindentedblock {margin-right: 0em; font-size: smaller} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smalllisp {margin-left: 3.2em} +kbd {font-style: oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nolinebreak {white-space: nowrap} +span.roman {font-family: initial; font-weight: normal} +span.sansserif {font-family: sans-serif; font-weight: normal} +ul.no-bullet {list-style: none} +@media (min-width: 1140px) { + body { + margin-left: 14rem; + margin-right: 4rem; + max-width: 52rem; + } +} + +@media (min-width: 800px) and (max-width: 1140px) { + body { + margin-left: 6rem; + margin-right: 4rem; + max-width: 52rem; + } +} + +@media (max-width: 800px) { + body { + margin: 1rem; + } +} + +--> +</style> +<link rel="stylesheet" type="text/css" href="https://dthompson.us/css/dthompson.css"> + + +</head> + +<body lang="en"> +<a name="Scripts"></a> +<div class="header"> +<p> +Next: <a href="Tweening.html#Tweening" accesskey="n" rel="next">Tweening</a>, Previous: <a href="Agendas.html#Agendas" accesskey="p" rel="prev">Agendas</a>, Up: <a href="Scripting.html#Scripting" accesskey="u" rel="up">Scripting</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html#Index" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="Scripts-1"></a> +<h4 class="subsection">2.4.2 Scripts</h4> + +<p>Now that we can schedule tasks, let’s take things to the next level. +It sure would be great if we could make procedures that described a +series of actions that happened over time, especially if we could do +so without contorting our code into a nest of callback procedures. +This is where scripts come in. With scripts we can write code in a +linear way, in a manner that appears to be synchronous, but with the +ability to suspend periodically in order to let other scripts have a +turn and prevent blocking the game loop. Building on top of the +scheduling that agendas provide, here is a script that models a child +trying to get their mother’s attention: +</p> +<div class="example"> +<pre class="example">(script + (while #t + (display "mom!") + (newline) + (sleep 60))) ; where 60 = 1 second of real time +</pre></div> + +<p>This code runs in an endless loop, but the <code>sleep</code> procedure +suspends the script and schedules it to be run later by the agenda. +So, after each iteration of the loop, control is returned back to the +game loop and the program is not stuck spinning in a loop that will +never exit. Pretty neat, eh? +</p> +<p>Scripts can suspend to any capable handler, not just the agenda. +The <code>yield</code> procedure will suspend the current script and pass +its “continuation” to a handler procedure. This handler procedure +could do anything. Perhaps the handler stashes the continuation +somewhere where it will be resumed when the user presses a specific +key on the keyboard, or maybe it will be resumed when the player picks +up an item off of the dungeon floor; the sky is the limit. +</p> +<p>Sometimes it is necessary to abruptly terminate a script after it has +been started. For example, when an enemy is defeated their AI routine +needs to be shut down. When a script is spawned, a handle to that +script is returned that can be used to cancel it when desired. +</p> +<div class="example"> +<pre class="example">(define script (script (while #t (display "hey\n") (sleep 60)))) +;; sometime later +(cancel-script script) +</pre></div> + +<dl> +<dt><a name="index-spawn_002dscript"></a>Procedure: <strong>spawn-script</strong> <em><var>thunk</var></em></dt> +<dd><p>Apply <var>thunk</var> as a script and return a handle to it. +</p></dd></dl> + +<dl> +<dt><a name="index-script"></a>Syntax: <strong>script</strong> <em><var>body</var> …</em></dt> +<dd><p>Evaluate <var>body</var> as a script and return a handle to it. +</p></dd></dl> + +<dl> +<dt><a name="index-script_003f"></a>Procedure: <strong>script?</strong> <em><var>obj</var></em></dt> +<dd><p>Return <code>#t</code> if <var>obj</var> is a script handle. +</p></dd></dl> + +<dl> +<dt><a name="index-script_002dcancelled_003f"></a>Procedure: <strong>script-cancelled?</strong> <em><var>obj</var></em></dt> +<dd><p>Return <code>#t</code> if <var>obj</var> has been cancelled. +</p></dd></dl> + +<dl> +<dt><a name="index-script_002drunning_003f"></a>Procedure: <strong>script-running?</strong> <em><var>obj</var></em></dt> +<dd><p>Return <code>#t</code> if <var>obj</var> has not yet terminated or been +cancelled. +</p></dd></dl> + +<dl> +<dt><a name="index-script_002dcomplete_003f"></a>Procedure: <strong>script-complete?</strong> <em><var>obj</var></em></dt> +<dd><p>Return <code>#t</code> if <var>obj</var> has terminated. +</p></dd></dl> + +<dl> +<dt><a name="index-cancel_002dscript"></a>Procedure: <strong>cancel-script</strong> <em><var>co</var></em></dt> +<dd><p>Prevent further execution of the script <var>co</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-yield"></a>Procedure: <strong>yield</strong> <em><var>handler</var></em></dt> +<dd><p>Suspend the current script and pass its continuation to the +procedure <var>handler</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-sleep"></a>Procedure: <strong>sleep</strong> <em><var>duration</var></em></dt> +<dd><p>Wait <var>duration</var> before resuming the current script. +</p></dd></dl> + +<dl> +<dt><a name="index-channel_002dget"></a>Procedure: <strong>channel-get</strong> <em><var>channel</var></em></dt> +<dd><p>Wait for a message from <var>channel</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-forever"></a>Syntax: <strong>forever</strong> <em><var>body</var> …</em></dt> +<dd><p>Evaluate <var>body</var> in an endless loop. +</p></dd></dl> + +<hr> +<div class="header"> +<p> +Next: <a href="Tweening.html#Tweening" accesskey="n" rel="next">Tweening</a>, Previous: <a href="Agendas.html#Agendas" accesskey="p" rel="prev">Agendas</a>, Up: <a href="Scripting.html#Scripting" accesskey="u" rel="up">Scripting</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html#Index" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |