(PHP 4 >= 4.0.6, PHP 5, PHP 7)
is_callable — Verify that the contents of a variable can be called as a function
is_callable ( mixed $var [, bool $syntax_only = false [, string &$callable_name ]] ) : bool
Verify that a value is a callable.
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.
Returns true
if var
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
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)
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https://www.php.net/manual/en/function.is-callable.php