is_callable

(PHP 4 >= 4.0.6, PHP 5, PHP 7)

is_callable — Verify that the contents of a variable can be called as a function

Description

bool is_callable ( mixed $var [, bool $syntax_only = false [, string &$callable_name ]] )

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.

Parameters

var

The value to check

syntax_only

If set to TRUE the function only verifies that name 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.

callable_name

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.

Return Values

Returns TRUE if var is callable, FALSE otherwise.

Examples

Example #1 is_callable() example

<?php
//??How?to?check?a?variable?to?see?if?it?can?be?called
//??as?a?function.

//
//??Simple?variable?containing?a?function
//

function?someFunction()?
{
}

$functionVariable?=?'someFunction';

var_dump(is_callable($functionVariable,?false,?$callable_name));??//?bool(true)

echo?$callable_name,?"\n";??//?someFunction

//
//??Array?containing?a?method
//

class?someClass?{

??function?someMethod()?
??{
??}

}

$anObject?=?new?someClass();

$methodVariable?=?array($anObject,?'someMethod');

var_dump(is_callable($methodVariable,?true,?$callable_name));??//??bool(true)

echo?$callable_name,?"\n";??//??someClass::someMethod

?>

Example #2 is_callable() and constructors

As of PHP 5.3.0 is_callable() reports constructors as not being callable. This affects PHP 5 style constructors (__construct) as well as PHP 4 style constructors (i.e. methods with the same name as the class). Formerly, both cases have been considered callable.

<?php

class?Foo
{
????public?function?__construct()?{}
????public?function?foo()?{}
}

var_dump(
????is_callable(array('Foo',?'__construct')),
????is_callable(array('Foo',?'foo'))
);

The above example will output:

bool(false)
bool(false)

Description

Parameters

Return Values

Examples

See Also