is_callable
(PHP 4 >= 4.0.6, PHP 5, PHP 7, PHP 8)
is_callable — 检测参数是否为合法的可调用结构
说明
验证变量的内容能否作为函数调用。 这可以检查包含有效函数名的变量，或者一个数组，包含了正确编码的对象以及函数名。
参数
-
name -
要检查的回调函数。
-
syntax_only -
如果设置为
true，这个函数仅仅验证name可能是函数或方法。 它仅仅拒绝非字符，或者未包含能用于回调函数的有效结构。有效的应该包含两个元素，第一个是一个对象或者字符，第二个元素是个字符。 -
callable_name -
接受“可调用的名称”。下面的例子是“someClass::someMethod”。 注意，尽管 someClass::SomeMethod() 的含义是可调用的静态方法，但例子的情况并不是这样的。
返回值
如果 name 可调用则返回 true，否则返回 false。
范例
示例 #1 is_callable() 例子
<?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 $callable_name, "\n"; // someClass::someMethod
?>
add a note
User Contributed Notes 6 notes
izharaazmi at gmail dot com ¶
6 years ago
If the target class has __call() magic function implemented, then is_callable will ALWAYS return TRUE for whatever method you call it.
is_callable does not evaluate your internal logic inside __call() implementation (and this is for good).
Therefore every method name is callable for such classes.
Hence it is WRONG to say (as someone said):
...is_callable will correctly determine the existence of methods made with __call...
Example:
<?php
class TestCallable
{
public function testing()
{
return "I am called.";
}
public function __call($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
?>
mohamed dot elidrissi at protonmail dot com ¶
11 months 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)
?>
jlh ¶
3 years ago
The story about __call() is a bit more complicated unfortunately. It will always return true ONLY if you pass an instance of a class, not if you pass the class name itself:
<?php
class MyClass {
public function method() { }
public function __call($name, $arguments) { }
}
is_callable([MyClass::class, 'method']); // true
is_callable([new MyClass(), 'method']); // true
is_callable([MyClass::class, 'other']); // false!!!
is_callable([new MyClass(), 'other'])); // true
rahadotaboulfethatgmail.com ¶
14 years ago
is_callable generates an [E_STRICT] error if the tested method cannot be called staticly. (and returns the good value)
I used @is_called
i'm using php 5.2.1
Quis strrev TA omicidio strrev TOD com ¶
14 years ago
is_callable() does _not_ check wheter this function is disabled by php.ini's disable_functions
use:
<?PHP
function is_disabled($function) {
$disabled_functions=explode(',',ini_get('disable_functions'));
return in_array($function, $disabled_functions);
}
?>
I`m running PHP 5.2.4
fgm at osinet dot fr ¶
10 years ago
Note that, for the purpose of this function, an abstract method, although necessarily non-callable since it does not have a body, is still considered to be callable:
<?php
abstract class Foo {
abstract function bar();
}
echo is_callable(array('Foo', 'bar'));
// display: 1
?>