is_callable

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

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

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.

Returns:

Returns TRUE if var is callable, FALSE otherwise.

Examples:

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
 
?>