php教程

class_uses

(PHP 5 >= 5.4.0, PHP 7)

class_uses — Return the traits used by the given class

说明

class_uses ( mixed $class [, bool $autoload = TRUE ] ) : array

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.

参数

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.

返回值

An array on success, or FALSE on error.

范例

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
)

参见

User Contributed Notes

Daniel Klein 23-Feb-2018 12:53
I have improved on ulf's improvement of stealz' code. I'm pretty sure the last "foreach" adds nothing, so I've removed it, as well as adding a check for string class names (as opposed to objects) to prevent the warning if the class is not found:

<?php
function class_uses_deep($class, $autoload = true) {
  $traits = [];

  // Get all the traits of $class and its parent classes
  do {
    $class_name = is_object($class)? get_class($class): $class;
    if (class_exists($class_name, $autoload)) {
      $traits = array_merge(class_uses($class, $autoload), $traits);
    }
  } while ($class = get_parent_class($class));

  // Get traits of all parent traits
  $traits_to_search = $traits;
  while (!empty($traits_to_search)) {
    $new_traits = class_uses(array_pop($traits_to_search), $autoload);
    $traits = array_merge($new_traits, $traits);
    $traits_to_search = array_merge($new_traits, $traits_to_search);
  };

  return array_unique($traits);
}
Daniel Klein 23-Feb-2018 12:48
If the class does not exist, you will get a warning, even if $autoload == false; I.e., if the class is not found, setting $autoload to false is not sufficient to silence the warning.

This is different from class_exists ($class_name, $autoload = true), which doesn't generate a warning in either case.
ulf 11-Jul-2013 09:21
A slighly modified version from Stealz that also checks all the "parent" traits used by the traits:

<?php
public static function class_uses_deep($class, $autoload = true)
    {
        $traits = [];

        // Get traits of all parent classes
        do {
            $traits = array_merge(class_uses($class, $autoload), $traits);
        } while ($class = get_parent_class($class));

        // Get traits of all parent traits
        $traitsToSearch = $traits;
        while (!empty($traitsToSearch)) {
            $newTraits = class_uses(array_pop($traitsToSearch), $autoload);
            $traits = array_merge($newTraits, $traits);
            $traitsToSearch = array_merge($newTraits, $traitsToSearch);
        };

        foreach ($traits as $trait => $same) {
            $traits = array_merge(class_uses($trait, $autoload), $traits);
        }

        return array_unique($traits);
    }
?>
adam at adamhahn dot com 30-Apr-2013 11:34
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

?>
stealz at op dot pl 01-Dec-2012 10:20
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);
}
?>

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