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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Verify that the contents of a variable can be called as a function</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.is-buffer.html">is_buffer</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.is-double.html">is_double</a></div> <div class="up"><a href="ref.var.html">Variable handling Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="function.is-callable" class="refentry"> <div class="refnamediv"> <h1 class="refname">is_callable</h1> <p class="verinfo">(PHP 4 >= 4.0.6, PHP 5)</p><p class="refpurpose"><span class="refname">is_callable</span> — <span class="dc-title"> Verify that the contents of a variable can be called as a function </span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">bool</span> <span class="methodname"><b><b>is_callable</b></b></span> ( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <tt class="parameter">$var</tt></span> [, <span class="methodparam"><span class="type">bool</span> <tt class="parameter">$syntax_only</tt></span> [, <span class="methodparam"><span class="type">string</span> <tt class="parameter reference">&$callable_name</tt></span> ]] )</div> <p class="para rdfs-comment"> Verify that the contents of a variable can be called as a function. This can check that a simple variable contains the name of a valid function, or that an array contains a properly encoded object and function name. </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><i><tt class="parameter">var</tt></i></span> <dd> <p class="para"> Can be either the name of a function stored in a string variable, or an object and the name of a method within the object, like this: <div class="example-contents"><pre>array($SomeObject, 'MethodName')</pre></div> </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">syntax_only</tt></i></span> <dd> <p class="para"> If set to <b><tt>TRUE</tt></b> the function only verifies that <i><tt class="parameter">var</tt></i> might be a function or method. It will only reject simple variables that are not strings, or an array that does not have a valid structure to be used as a callback. The valid ones are supposed to have only 2 entries, the first of which is an object or a string, and the second a string. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">callable_name</tt></i></span> <dd> <p class="para"> Receives the "callable name". In the example below it is "someClass::someMethod". Note, however, that despite the implication that someClass::SomeMethod() is a callable static method, this is not the case. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns <b><tt>TRUE</tt></b> if <i><tt class="parameter">var</tt></i> is callable, <b><tt>FALSE</tt></b> otherwise. </p> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 <b>is_callable()</b> example</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// How to check a variable to see if it can be called<br />// as a function.<br /><br />//<br />// Simple variable containing a function<br />//<br /><br /></span><span style="color: #007700">function </span><span style="color: #0000BB">someFunction</span><span style="color: #007700">() <br />{<br />}<br /><br /></span><span style="color: #0000BB">$functionVariable </span><span style="color: #007700">= </span><span style="color: #DD0000">'someFunction'</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">is_callable</span><span style="color: #007700">(</span><span style="color: #0000BB">$functionVariable</span><span style="color: #007700">, </span><span style="color: #0000BB">false</span><span style="color: #007700">, </span><span style="color: #0000BB">$callable_name</span><span style="color: #007700">)); </span><span style="color: #FF8000">// bool(true)<br /><br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">$callable_name</span><span style="color: #007700">, </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">; </span><span style="color: #FF8000">// someFunction<br /><br />//<br />// Array containing a method<br />//<br /><br /></span><span style="color: #007700">class </span><span style="color: #0000BB">someClass </span><span style="color: #007700">{<br /><br /> function </span><span style="color: #0000BB">someMethod</span><span style="color: #007700">() <br /> {<br /> }<br /><br />}<br /><br /></span><span style="color: #0000BB">$anObject </span><span style="color: #007700">= new </span><span style="color: #0000BB">someClass</span><span style="color: #007700">();<br /><br /></span><span style="color: #0000BB">$methodVariable </span><span style="color: #007700">= array(</span><span style="color: #0000BB">$anObject</span><span style="color: #007700">, </span><span style="color: #DD0000">'someMethod'</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">is_callable</span><span style="color: #007700">(</span><span style="color: #0000BB">$methodVariable</span><span style="color: #007700">, </span><span style="color: #0000BB">true</span><span style="color: #007700">, </span><span style="color: #0000BB">$callable_name</span><span style="color: #007700">)); </span><span style="color: #FF8000">// bool(true)<br /><br /></span><span style="color: #007700">echo </span><span style="color: #0000BB">$callable_name</span><span style="color: #007700">, </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">; </span><span style="color: #FF8000">// someClass::someMethod<br /><br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </p> </div> <div class="refsect1 seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"><a href="function.function-exists.html" class="function" rel="rdfs-seeAlso">function_exists()</a></li> <li class="member"><a href="function.method-exists.html" class="function" rel="rdfs-seeAlso">method_exists()</a></li> </ul> </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.is-buffer.html">is_buffer</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.is-double.html">is_double</a></div> <div class="up"><a href="ref.var.html">Variable handling Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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