(PHP 5 >= 5.4.0)
class_uses — Return the traits used by the given class
This function returns an array with the names of the traits that the
given class uses. This does however not include
any traits used by a parent class.
class
An object (class instance) or a string (class name).
autoload
Whether to allow this function to load the class automatically through the __autoload() magic method.
An array on success, or FALSE on error.
Example #1 class_uses() example
<?php
trait foo { }
class bar {
use foo;
}
print_r(class_uses(new bar));
print_r(class_uses('bar'));
function __autoload($class_name) {
require_once $class_name . '.php';
}
// use __autoload to load the 'not_loaded' class
print_r(class_uses('not_loaded', true));
?>
以上例程的输出类似于：
Array
(
[foo] => foo
)
Array
(
[foo] => foo
)
Array
(
[trait_of_not_loaded] => trait_of_not_loaded
)
adam at adamhahn dot com (2013-05-02 00:29:13)
This function can be used on traits as well as classes. Since traits 'use' other traits to create inheritance, this function allows you to get the parent trait(s) of another trait.
<?php
trait foo {
}
trait child {
use foo;
}
print_r(class_uses('child')); // Outputs array containing 'foo'
?>
adam at adamhahn dot com (2013-04-30 23:34:51)
FYI: It is not explicitly stated, but if you run this function against a class that does not use any traits it will return an empty array.
<?php
class iDontUseTraits {
}
class_uses('iDontUseTraits'); // Returns empty array
?>
benkuhl at gmail dot com (2012-12-21 23:55:52)
[Edited by: googleguy at php dot net for clarity. It's obvious Xyz should have been Trait and not Class. ]
If your objective is to determine if a trait is being used by another class, you cannot use instanceOf...
<?php
Trait Xyz {
}
class Abc {
use Xyz;
}
$abc = new Abc();
var_dump($abc instanceOf Xyz); // false
?>
You must use this function with either an in_array or array_key_exists...
<?php
var_dump(array_key_exists('Xyz', class_uses($abc))); //true
?>
stealz at op dot pl (2012-12-01 10:20:58)
To get ALL traits including those used by parent classes and other traits, use this function:
<?php
function class_uses_deep($class, $autoload = true) {
$traits = [];
do {
$traits = array_merge(class_uses($class, $autoload), $traits);
} while($class = get_parent_class($class));
foreach ($traits as $trait => $same) {
$traits = array_merge(class_uses($trait, $autoload), $traits);
}
return array_unique($traits);
}
?>