PHP Reference

Description

bool is_callable ( mixed var [, bool syntax_only [, 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.

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:
array($SomeObject, 'MethodName')

If the syntax_only argument is 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.

The callable_name 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.


<?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



?>