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is_callable documented as suggested in user note / bug #21124

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credits go to php4 at developersdesk dot com


git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@134197 c90b9560-bf6c-de11-be94-00142212c4b1
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Hartmut Holzgraefe 2003-07-04 21:43:55 +00:00
parent 7142de1cfb
commit 37b74f7578
1 changed files with 60 additions and 39 deletions
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99
reference/var/functions/is-callable.xml
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@ -1,11 +1,11 @@
<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.3 $ -->
<!-- $Revision: 1.4 $ -->
<!-- splitted from ./en/functions/var.xml, last change in rev 1.87 -->
<refentry id="function.is-callable">
<refnamediv>
<refname>is_callable</refname>
<refpurpose>
Find out whether the argument is a valid callable construct
Verify that the contents of a variable can be called as a function
</refpurpose>
</refnamediv>
<refsect1>
@ -17,55 +17,76 @@
<methodparam choice="opt"><type>string</type><parameter>callable_name</parameter></methodparam>
</methodsynopsis>
<para>
&warn.undocumented.func;
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.
</para>
<!--
<simpara>
The <parameter>var</parameter> parameter is the name of a function or method.
Also, class or object methods are specified by passing a numerical array with
two elements: the class or object, and a method name.
</simpara>
<simpara>
The optional <parameter>syntax_only</parameter> parameter will check
only for syntax and defaults to &false; The third <parameter>
callable_name</parameter> parameter is also optional.
</simpara>
<para>
In our example below note, however, that despite the implication that
<literal>a::b()</literal> is a callable static method, this is not the
case.
<example>
<title>Using <function>is_callable</function></title>
<programlisting role="php">
The var parameter 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:
<screen>array( $SomeObject, 'MethodName' )</screen>
</para>
<para>
If the <parameter>syntax_only</parameter> argument is &true; the
function only verifies that <parameter>var</parameter> 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.
</para>
<para>
The <parameter>callable_name</parameter> argument receives the
"callable name". In the example below it's
"someClass:someMethod". Note, however, that despite the
implication that someClass::SomeMethod() is a callable static
method, this is not the case.
</para>
<informalexample>
<programlisting>
<![CDATA[
<?php
class a
{
var $c;
function b() {
return($this->c);
}
<? php
// How to check a variable to see if it can be called
// as a function.
//
// Simple variable containing a function
//
function someFunction() {
}
$d = new a;
$functionVariable = 'someFunction';
if(is_callable(array($d, 'b'), FALSE, $name)) {
var_dump( is_callable( $functionVariable, false, $callable_name )); // bool(true)
echo $callable_name, "\n"; // someFunction
//
// Array containing a method
//
class someClass {
function someMethod() {
}
echo $name;
}
/* The above will print:
a::
$anObject = new someClass();
$methodVariable = array( $anObject, 'someMethod' );
var_dump( is_callable( $methodVariable, true, $callable_name )); // bool(true)
echo $callable_name, "\n"; // someClass:someMethod
*/
?>
]]>
</programlisting>
</example>
</para>
-->
</programlisting>
</informalexample>
</refsect1>
</refentry>