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<h2 class="title">Rules</h2>
<p class="para">
The following list gives an overview of which rights the PHP project
reserves for itself, when choosing names for new internal identifiers.
The definitive guide is the official
<a href="http://git.php.net/?p=php-src.git;a=blob_plain;f=CODING_STANDARDS;hb=HEAD" class="link external">» CODING STANDARDS</a>:
</p>
<ul class="itemizedlist">
<li class="listitem">
<p class="para">
PHP owns the top-level namespace but tries to find decent descriptive
names and avoid any obvious clashes.
</p>
</li>
<li class="listitem">
<p class="para">
Function names use underscores between words, while class names use
both the <em>camelCase</em> and <em>PascalCase</em>
rules.
</p>
</li>
<li class="listitem">
<p class="para">
PHP will prefix any global symbols of an extension with the name of
the extension. (In the past, there have been numerous
exceptions to this rule.) Examples:
</p>
<ul class="itemizedlist">
<li class="listitem"><p class="para"> <span class="function"><a href="function.curl-close.html" class="function">curl_close()</a></span></p></li>
<li class="listitem"><p class="para"> <span class="function"><a href="function.mysql-query.html" class="function">mysql_query()</a></span></p></li>
<li class="listitem"><p class="para">PREG_SPLIT_DELIM_CAPTURE</p></li>
<li class="listitem"><p class="para">new DOMDocument()</p></li>
<li class="listitem">
<p class="para">
<span class="function"><a href="function.strpos.html" class="function">strpos()</a></span> (example of a past mistake)
</p>
</li>
<li class="listitem"><p class="para">new SplFileObject()</p></li>
</ul>
</li>
<li class="listitem">
<p class="para">
Iterators and Exceptions are however simply postfixed with
"<em>Iterator</em>" and "<em>Exception</em>."
Examples:
</p>
<ul class="itemizedlist">
<li class="listitem"><p class="para"><a href="class.arrayiterator.html" class="classname">ArrayIterator</a></p></li>
<li class="listitem"><p class="para"><a href="class.logicexception.html" class="classname">LogicException</a></p></li>
</ul>
</li>
<li class="listitem">
<p class="para">
PHP reserves all symbols starting with <em>__</em>
as magical. It is recommended that you do not create symbols starting
with <em>__</em> in PHP unless
you want to use documented magical functionality. Examples:
</p>
<ul class="itemizedlist">
<li class="listitem"><p class="para"><a href="language.oop5.overloading.html#object.get" class="link">__get()</a></p></li>
<li class="listitem"><p class="para"> <span class="function"><a href="function.autoload.html" class="function">__autoload()</a></span></p></li>
</ul>
</li>
</ul>
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