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.

    Опис

    is_callable(mixed $value, bool $syntax_only = false, string &$callable_name = null): bool

    Verify that a value is a callable.

    Параметри

    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.

    Значення, що повертаються

    Returns true if value is callable, false otherwise.

    Приклади

    Приклад #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

    ?>

    Приклад #2 is_callable() and constructors

    is_callable() reports constructors as not being callable.

    <?php

    class Foo
    {
    public function     __construct() {}
    public function     foo() {}
    }

    var_dump(
    is_callable(array('Foo', '__construct')),
    is_callable(array('Foo', 'foo'))
    );

    Поданий вище приклад виведе:

    bool(false)
bool(false)

    Примітки

    • 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 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.

    Прогляньте також

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    User Contributed Notes 2 notes

    up
    35
    izharaazmi at gmail dot com
    8 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)

    echo is_callable(array($t, 'testing')); // Output: TRUE
    echo is_callable(array($t, 'testingOther')); // Output: TRUE
    echo is_callable(array($t, 'working')); // Output: TRUE, expected: FALSE
    ?>
    up
    19
    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

    class Test
    {
    public function     method1() { }
    public static function     method2() { }
    }

    // Pre PHP 8
    var_dump(is_callable(array('Test', 'method1'))); // bool(true)
    var_dump(is_callable(array('Test', 'method2'))); // bool(true)

    // Post PHP 8
    var_dump(is_callable(array('Test', 'method1'))); // bool(false)
    var_dump(is_callable(array('Test', 'method2'))); // bool(true)
    var_dump(is_callable(array(new Test, 'method1'))); // bool(true)

    ?>
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