Summary: 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])Description
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.
Return: bool
Returns TRUE if var is callable, FALSE otherwise.
Parameters
Mandatory
- mixed $var: The value to check
Optional
- bool $syntax_only [ = false]: If set to
TRUEthe function only verifies thatnamemight be a function or method. It will only reject simple variables that are not strings, or an array that does not have a valid structure to be used as a callback. The valid ones are supposed to have only 2 entries, the first of which is an object or a string, and the second a string. - string &$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.
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)