Php/docs/function.is-callable

• PHP Manual
• Variable handling Functions
• Verify that the contents of a variable can be called as a function

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

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

Verify that a value is a callable.

Parameters

var

The value to check

syntax_only

If set to TRUE the function only verifies that var 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.

<?phpclass 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)

See Also

• function_exists() - Return TRUE if the given function has been defined
• method_exists() - Checks if the class method exists