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diff --git a/manuals/chickadee/Agendas.html b/manuals/chickadee/Agendas.html new file mode 100644 index 0000000..eced92c --- /dev/null +++ b/manuals/chickadee/Agendas.html @@ -0,0 +1,221 @@ +<!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>Agendas (The Chickadee Game Toolkit)</title> + +<meta name="description" content="Agendas (The Chickadee Game Toolkit)"> +<meta name="keywords" content="Agendas (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="Scripts.html#Scripts" rel="next" title="Scripts"> +<link href="Scripting.html#Scripting" rel="prev" title="Scripting"> +<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="Agendas"></a> +<div class="header"> +<p> +Next: <a href="Scripts.html#Scripts" accesskey="n" rel="next">Scripts</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="Agendas-1"></a> +<h4 class="subsection">2.4.1 Agendas</h4> + +<p>To schedule a task to be performed later, an “agenda” is used. +There is a default, global agenda that is ready to be used, or +additional agendas may be created for different purposes. The +following example prints the text “hello” when the agenda has +advanced to time unit 10. +</p> +<div class="example"> +<pre class="example">(at 10 (display "hello\n")) +</pre></div> + +<p>Most of the time it is more convenient to schedule tasks relative to +the current time. This is where <code>after</code> comes in handy: +</p> +<div class="example"> +<pre class="example">(after 10 (display "hello\n")) +</pre></div> + +<p>Time units in the agenda are in no way connected to real time. It’s +up to the programmer to decide what agenda time means. A simple and +effective approach is to map each call of the update hook +(see <a href="Kernel.html#Kernel">Kernel</a>) to 1 unit of agenda time, like so: +</p> +<div class="example"> +<pre class="example">(add-hook! update-hook (lambda (dt) (update-agenda 1))) +</pre></div> + +<p>It is important to call <code>update-agenda</code> periodically, otherwise +no tasks will ever be run! +</p> +<p>In addition to using the global agenda, it is useful to have multiple +agendas for different purposes. For example, the game world can use a +different agenda than the user interface, so that pausing the game is +a simple matter of not updating the world’s agenda while continuing to +update the user interface’s agenda. The current agenda is dynamically +scoped and can be changed using the <code>with-agenda</code> special form: +</p> +<div class="example"> +<pre class="example">(define game-world-agenda (make-agenda)) + +(with-agenda game-world-agenda + (at 60 (spawn-goblin)) + (at 120 (spawn-goblin)) + (at 240 (spawn-goblin-king))) +</pre></div> + +<dl> +<dt><a name="index-make_002dagenda"></a>Procedure: <strong>make-agenda</strong></dt> +<dd><p>Return a new task scheduler. +</p></dd></dl> + +<dl> +<dt><a name="index-agenda_003f"></a>Procedure: <strong>agenda?</strong> <em><var>obj</var></em></dt> +<dd><p>Return <code>#t</code> if <var>obj</var> is an agenda. +</p></dd></dl> + +<dl> +<dt><a name="index-current_002dagenda"></a>Procedure: <strong>current-agenda</strong></dt> +<dt><a name="index-current_002dagenda-1"></a>Procedure: <strong>current-agenda</strong> <em><var>agenda</var></em></dt> +<dd><p>When called with no arguments, return the current agenda. When called +with one argument, set the current agenda to <var>agenda</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-with_002dagenda"></a>Syntax: <strong>with-agenda</strong> <em><var>agenda</var> <var>body</var> …</em></dt> +<dd><p>Evaluate <var>body</var> with the current agenda set to <var>agenda</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-agenda_002dtime"></a>Procedure: <strong>agenda-time</strong></dt> +<dd><p>Return the current agenda time. +</p></dd></dl> + +<dl> +<dt><a name="index-update_002dagenda"></a>Procedure: <strong>update-agenda</strong> <em><var>dt</var></em></dt> +<dd><p>Advance the current agenda by <var>dt</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-schedule_002dat"></a>Procedure: <strong>schedule-at</strong> <em><var>time</var> <var>thunk</var></em></dt> +<dd><p>Schedule <var>thunk</var>, a procedure of zero arguments, to be run at +<var>time</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-schedule_002dafter"></a>Procedure: <strong>schedule-after</strong> <em><var>delay</var> <var>thunk</var></em></dt> +<dd><p>Schedule <var>thunk</var>, a procedure of zero arguments, to be run after +<var>delay</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-schedule_002devery"></a>Procedure: <strong>schedule-every</strong> <em><var>interval</var> <var>thunk</var> [<var>n</var>]</em></dt> +<dd><p>Schedule <var>thunk</var>, a procedure of zero arguments, to be run every +<var>interval</var> amount of time. Repeat this <var>n</var> times, or +indefinitely if not specified. +</p></dd></dl> + +<dl> +<dt><a name="index-at"></a>Syntax: <strong>at</strong> <em><var>time</var> <var>body</var> …</em></dt> +<dd><p>Schedule <var>body</var> to be evaluated at <var>time</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-after"></a>Syntax: <strong>after</strong> <em><var>delay</var> <var>body</var> …</em></dt> +<dd><p>Schedule <var>body</var> to be evaluated after <var>delay</var>. +</p></dd></dl> + +<dl> +<dt><a name="index-every"></a>Syntax: <strong>every</strong> <em><var>interval</var> <var>body</var> …</em></dt> +<dt><a name="index-every-1"></a>Syntax: <strong>every</strong> <em>(<var>interval</var> <var>n</var>) <var>body</var> …</em></dt> +<dd><p>Schedule <var>body</var> to be evaluated every <var>interval</var> amount of +time. Repeat this <var>n</var> times, or indefinitely if not specified. +</p></dd></dl> + +<hr> +<div class="header"> +<p> +Next: <a href="Scripts.html#Scripts" accesskey="n" rel="next">Scripts</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> |