A rudimentary implementation of Ruby's tap(), generally useful for basic debugging.

PHP tap()

/*
 * To be used with
 * <https://github.com/wellspringworldwide/PHP-ClassMixer>
 */
abstract class Tapable_Mixin {
    public function tap($var_of_this, $eval) {
        $$var_of_this = $this;
        eval($eval);
    }
}