(PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8)
is_callable — Verify that a value can be called as a function from the current scope.
Verify that a value is a callable.
value
The value to check
syntax_only
If set to true
the function only verifies that
value
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 true
if value
is callable, false
otherwise.
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
is_callable() reports constructors as not being 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)
true
for any method on that object, even if the method is not defined.