PHP: Hypertext Preprocessor (original) (raw)

is_callable

(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

Description

Parameters

value

The value to be checked.

syntax_only

If set to [true](reserved.constants.php#constant.true) the function only verifies thatvalue might be a function or method. It will reject any values that are not invokable objects,Closure, strings, or arrays that do not have a valid structure to be used as a callback. A valid callable array has 2 entries, the first of which is an object or a string, and the second a string.

callable_name

Receives the "callable name", e.g."SomeClass::someMethod". Note, however, that despite the implication that SomeClass::someMethod() is a callable static method, this is not the case.

Return Values

Returns [true](reserved.constants.php#constant.true) if value is callable, [false](reserved.constants.php#constant.false) otherwise.

Examples

Example #1 Checking whether a string can be called as a function

<?phpfunction someFunction() {}$functionVariable = 'someFunction';var_dump(is_callable($functionVariable, false, <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>c</mi><mi>a</mi><mi>l</mi><mi>l</mi><mi>a</mi><mi>b</mi><mi>l</mi><msub><mi>e</mi><mi>n</mi></msub><mi>a</mi><mi>m</mi><mi>e</mi><mo stretchy="false">)</mo><mo stretchy="false">)</mo><mo separator="true">;</mo><mi>v</mi><mi>a</mi><msub><mi>r</mi><mi>d</mi></msub><mi>u</mi><mi>m</mi><mi>p</mi><mo stretchy="false">(</mo></mrow><annotation encoding="application/x-tex">callable_name));var_dump(</annotation></semantics></math>callablename));vardump(callable_name);?>

The above example will output:

bool(true) string(12) "someFunction"

Example #2 Checking whether an array can be called as a function

<?phpclass SomeClass { public function someMethod() {} }$anObject = new SomeClass();$methodVariable = [$anObject, 'someMethod'];var_dump(is_callable($methodVariable, true, <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>c</mi><mi>a</mi><mi>l</mi><mi>l</mi><mi>a</mi><mi>b</mi><mi>l</mi><msub><mi>e</mi><mi>n</mi></msub><mi>a</mi><mi>m</mi><mi>e</mi><mo stretchy="false">)</mo><mo stretchy="false">)</mo><mo separator="true">;</mo><mi>v</mi><mi>a</mi><msub><mi>r</mi><mi>d</mi></msub><mi>u</mi><mi>m</mi><mi>p</mi><mo stretchy="false">(</mo></mrow><annotation encoding="application/x-tex">callable_name));var_dump(</annotation></semantics></math>callablename));vardump(callable_name);?>

The above example will output:

bool(true) string(21) "SomeClass::someMethod"

Example #3 is_callable() and constructors

Despite the fact that constructors are the methods that are called when an object is created, they are not static methods andis_callable() will return [false](reserved.constants.php#constant.false) for them. It's not possible to use is_callable() to check if a class can be instantiated from the current scope.

`<?phpclass Foo
{
public function __construct() {}

public function

foo() {}
}var_dump(
is_callable(['Foo', '__construct']),
is_callable(['Foo', 'foo'])
);$foo = new Foo();
var_dump(is_callable([$foo, '__construct']));?>`

The above example will output:

bool(false) bool(false) bool(true)

Notes

An object is always callable if it implements __invoke(), and that method is visible in the current scope.
A class name is callable if it implements __callStatic().
If an object implements __call(), then this function will return [true](reserved.constants.php#constant.true) for any method on that object, even if the method is not defined.
This function may trigger autoloading if called with the name of a class.

Found A Problem?

izharaazmi at gmail dot com ¶

9 years ago

`If the target class has __call() magic function implemented, then is_callable will ALWAYS return TRUE for whatever method you call it.
is_callable does not evaluate your internal logic inside __call() implementation (and this is for good).
Therefore every method name is callable for such classes.

Hence it is WRONG to say (as someone said):
...is_callable will correctly determine the existence of methods made with __call...

Example:
<?php
class TestCallable
{
public function testing()
{
return "I am called.";
}

public function

__call($name, $args)
{
if($name == 'testingOther')
{
return call_user_func_array(array($this, 'testing'), $args);
}
}
}$t = new TestCallable();
echo $t->testing(); // Output: I am called.
echo $t->testingOther(); // Output: I am called.
echo t−>working();//Output:(null)echoiscallable(array(t->working(); // Output: (null)echo is_callable(array(t−>working();//Output:(null)echoiscallable(array(t, 'testing')); // Output: TRUE
echo is_callable(array($t, 'testingOther')); // Output: TRUE
echo is_callable(array($t, 'working')); // Output: TRUE, expected: FALSE
?>

mohamed dot elidrissi at protonmail dot com ¶

3 years ago

`Note that -- as mentioned in the migration guide-- starting from PHP 8.0, is_callable() will not work with non-static methods if you use a class name, instead an object of the class should be provided:

PHP: Hypertext Preprocessor (original) (raw)

is_callable

Description

Parameters

Return Values

Examples

Notes

See Also

Found A Problem?