Mixed

A special type that represents any available type. It is equivalent to not explicitly setting the type, though it is now explicitly done.

A mixed type may be also represented by a union of all possible types.

mixed is useful when literally any type should be supported, such as with a cache system. Yet, it is usually recommended to consider reducing the number of possible types by using a common interface or a union type.

<?php

    function cache(string $name, mixed $value) : bool {
        static $cache = [];
        
        $cache[$name] = $value;
        
        return true;
    }

?>

Documentation

See Also

• Mixed Type PHP 8
• A mixed type PHPStan journey
• Why mixed Is the Worst Type in Your PHP Codebase (and How to Kill It)

Related

• Type System
• Pseudo-type
• Special Types
• Type Inference
• Wildcard