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<h1>Penlight</h1>
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<h2>Contents</h2>
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<li><a href="#Functions">Functions</a></li>
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<h2>Libraries</h2>
<ul class="$(kind=='Topics' and '' or 'nowrap'">
<li><a href="../libraries/pl.html">pl</a></li>
<li><a href="../libraries/pl.Set.html">pl.Set</a></li>
<li><a href="../libraries/pl.app.html">pl.app</a></li>
<li><a href="../libraries/pl.array2d.html">pl.array2d</a></li>
<li><strong>pl.class</strong></li>
<li><a href="../libraries/pl.compat.html">pl.compat</a></li>
<li><a href="../libraries/pl.comprehension.html">pl.comprehension</a></li>
<li><a href="../libraries/pl.config.html">pl.config</a></li>
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<li><a href="../libraries/pl.lexer.html">pl.lexer</a></li>
<li><a href="../libraries/pl.luabalanced.html">pl.luabalanced</a></li>
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<li><a href="../libraries/pl.seq.html">pl.seq</a></li>
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<li><a href="../classes/pl.Date.html">pl.Date</a></li>
<li><a href="../classes/pl.List.html">pl.List</a></li>
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<li><a href="../classes/pl.MultiMap.html">pl.MultiMap</a></li>
<li><a href="../classes/pl.OrderedMap.html">pl.OrderedMap</a></li>
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<h2>Manual</h2>
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<li><a href="../manual/01-introduction.md.html">Introduction</a></li>
<li><a href="../manual/02-arrays.md.html">Tables and Arrays</a></li>
<li><a href="../manual/03-strings.md.html">Strings. Higher-level operations on strings.</a></li>
<li><a href="../manual/04-paths.md.html">Paths and Directories</a></li>
<li><a href="../manual/05-dates.md.html">Date and Time</a></li>
<li><a href="../manual/06-data.md.html">Data</a></li>
<li><a href="../manual/07-functional.md.html">Functional Programming</a></li>
<li><a href="../manual/08-additional.md.html">Additional Libraries</a></li>
<li><a href="../manual/09-discussion.md.html">Technical Choices</a></li>
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<h2>Examples</h2>
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<li><a href="../examples/seesubst.lua.html">seesubst.lua</a></li>
<li><a href="../examples/sipscan.lua.html">sipscan.lua</a></li>
<li><a href="../examples/symbols.lua.html">symbols.lua</a></li>
<li><a href="../examples/test-cmp.lua.html">test-cmp.lua</a></li>
<li><a href="../examples/test-data.lua.html">test-data.lua</a></li>
<li><a href="../examples/test-listcallbacks.lua.html">test-listcallbacks.lua</a></li>
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<li><a href="../examples/testconfig.lua.html">testconfig.lua</a></li>
<li><a href="../examples/testglobal.lua.html">testglobal.lua</a></li>
<li><a href="../examples/testinputfields.lua.html">testinputfields.lua</a></li>
<li><a href="../examples/testinputfields2.lua.html">testinputfields2.lua</a></li>
<li><a href="../examples/testxml.lua.html">testxml.lua</a></li>
<li><a href="../examples/which.lua.html">which.lua</a></li>
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<h1>Module <code>pl.class</code></h1>
<p>Provides a reuseable and convenient framework for creating classes in Lua.</p>
<p> Two possible notations:</p>
<pre>
B = class(A)
class.B(A)
</pre>
<p> The latter form creates a named class within the current environment. Note
that this implicitly brings in <a href="../libraries/pl.utils.html#">pl.utils</a> as a dependency.</p>
<p> See the Guide for further <a href="../manual/01-introduction.md.html#Simplifying_Object_Oriented_Programming_in_Lua">discussion</a></p>
<h2><a href="#Functions">Functions</a></h2>
<table class="function_list">
<tr>
<td class="name" nowrap><a href="#_init">_init (...)</a></td>
<td class="summary">initializes an <strong>instance</strong> upon creation.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#instance:is_a">instance:is_a (some_class)</a></td>
<td class="summary">checks whether an <strong>instance</strong> is derived from some class.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#some_class:class_of">some_class:class_of (some_instance)</a></td>
<td class="summary">checks whether an <strong>instance</strong> is derived from some class.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#some_class:cast">some_class:cast (some_instance)</a></td>
<td class="summary">cast an object to another class.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#class">class (base, c_arg, c)</a></td>
<td class="summary">create a new class, derived from a given base class.</td>
</tr>
</table>
<br/>
<br/>
<h2><a name="Functions"></a>Functions</h2>
<dl class="function">
<dt>
<a name = "_init"></a>
<strong>_init (...)</strong>
</dt>
<dd>
initializes an <strong>instance</strong> upon creation.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">...</span>
parameters passed to the constructor
</li>
</ul>
<h3>Usage:</h3>
<ul>
<pre class="example"> <span class="keyword">local</span> Cat = class()
<span class="keyword">function</span> Cat:_init(name)
<span class="comment">--self:super(name) -- call the ancestor initializer if needed
</span> self.name = name
<span class="keyword">end</span>
<span class="keyword">local</span> pussycat = Cat(<span class="string">"pussycat"</span>)
<span class="global">print</span>(pussycat.name) --> pussycat</pre>
</ul>
</dd>
<dt>
<a name = "instance:is_a"></a>
<strong>instance:is_a (some_class)</strong>
</dt>
<dd>
checks whether an <strong>instance</strong> is derived from some class.
Works the other way around as <a href="../libraries/pl.class.html#some_class:class_of">class_of</a>.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">some_class</span>
class to check against
</li>
</ul>
<h3>Returns:</h3>
<ol>
<code>true</code> if <code>instance</code> is derived from <code>some_class</code>
</ol>
<h3>Usage:</h3>
<ul>
<pre class="example"> <span class="keyword">local</span> pussycat = Lion() <span class="comment">-- assuming Lion derives from Cat
</span> <span class="keyword">if</span> pussycat:is_a(Cat) <span class="keyword">then</span>
<span class="comment">-- it's true
</span> <span class="keyword">end</span></pre>
</ul>
</dd>
<dt>
<a name = "some_class:class_of"></a>
<strong>some_class:class_of (some_instance)</strong>
</dt>
<dd>
checks whether an <strong>instance</strong> is derived from some class.
Works the other way around as <a href="../libraries/pl.class.html#instance:is_a">is_a</a>.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">some_instance</span>
instance to check against
</li>
</ul>
<h3>Returns:</h3>
<ol>
<code>true</code> if <code>some_instance</code> is derived from <code>some_class</code>
</ol>
<h3>Usage:</h3>
<ul>
<pre class="example"> <span class="keyword">local</span> pussycat = Lion() <span class="comment">-- assuming Lion derives from Cat
</span> <span class="keyword">if</span> Cat:class_of(pussycat) <span class="keyword">then</span>
<span class="comment">-- it's true
</span> <span class="keyword">end</span></pre>
</ul>
</dd>
<dt>
<a name = "some_class:cast"></a>
<strong>some_class:cast (some_instance)</strong>
</dt>
<dd>
cast an object to another class.
It is not clever (or safe!) so use carefully.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">some_instance</span>
the object to be changed
</li>
</ul>
</dd>
<dt>
<a name = "class"></a>
<strong>class (base, c_arg, c)</strong>
</dt>
<dd>
create a new class, derived from a given base class.
Supporting two class creation syntaxes:
either <code>Name = class(base)</code> or <code>class.Name(base)</code>.
The first form returns the class directly and does not set its <code>_name</code>.
The second form creates a variable <code>Name</code> in the current environment set
to the class, and also sets <code>_name</code>.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">base</span>
optional base class
</li>
<li><span class="parameter">c_arg</span>
optional parameter to class constructor
</li>
<li><span class="parameter">c</span>
optional table to be used as class
</li>
</ul>
</dd>
</dl>
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