Example #1 class_uses() example

The above example will output something similar to:

Array
(
    [foo] => foo
)
Array
(
    [foo] => foo
)
Array
(
    [trait_of_not_loaded] => trait_of_not_loaded
)

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);
}
?>

Another alternative to get all parent traits is:

<?php
function getUsedTraits($classInstance) {
    $parentClasses = class_parents($classInstance);
    $traits = class_uses($classInstance);
    
    foreach ($parentClasses as $parentClass) {
        $traits = array_merge($traits, class_uses($parentClass));
    }
    
    return $traits;
}
?>

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);
    }
?>

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.

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);
}

The popular stealz solution doesn't handle traits that use other traits. A little bit of recursion can clean the entire thing up a bit and make it more robust.

<?php

public function class_uses_deep( string $class, bool $autoload = true ) : array {
    $traits = class_uses($class, $autoload);

    if($parent = get_parent_class($class)) {
        $traits = array_merge($traits, class_uses_deep($parent, $autoload));
    }

    foreach( $traits as $trait ) {
        $traits = array_merge($traits, class_uses_deep($trait, $autoload));
    }

    return $traits;
}

?>