get_declared_traits - PHP code example

Attributes and the php Function Get_Declared_Traits

Functions are a powerful programming construct that enable us to encapsulate a block of code that can be reused in the program. Functions are executed by passing them arguments, which is a piece of information that the function can act upon or consume in order to perform its task.

Attributes are a new addition in PHP 8, allowing developers to declare and fetch small pieces of meta-data about classes, functions, closures, class methods, constants and even anonymous classes in a structured way. Many frameworks such as Symfony, Drupal, and Doctrine use Annotations today to provide auxiliary information about a certain class in an organized manner, but Attributes take this concept one step further by providing a native engine-validated implementation.

Attribute values can be either simple scalar types or even arrays. They can also have a number of built-in properties that will be automatically resolved and auto-loaded when an instance of an Attribute is requested.

The php function get_declared_traits retrieves an associative array of all declared traits in a given scope. It returns the names of all traits used by a given class, excluding those that are used by its parent class. The return value is NULL if not found.

get_declared_traits example

$prev = [];

        try {
            while ($prev !== $classes) {
                $prev = $classes;
                foreach ($classes as $c) {
                    if (!isset($preloaded[$c])) {
                        self::doPreload($c, $preloaded);
                    }
                }
                $classes = array_merge(get_declared_classes(), get_declared_interfaces(), get_declared_traits());
            }
        } finally {
            restore_error_handler();
        }

        return $preloaded;
    }

    private static function doPreload(string $class, array &$preloaded): void
    {
        if (isset($preloaded[$class]) || \in_array($class, ['self', 'static', 'parent'], true)) {