PEAR_Callback proposal

Hi, A couple of days ago I proposed the package PEAR_Callback; see http://pear.php.net/pepr/pepr-proposal-show.php?id=468 It addresses three major limitations of the callback pseudo-type: - By looking at a callback pseudo-type variable you cannot tell if it really is a callback. - The callback pseudo-type does not allow you to specify arguments at the time you create the callback. - There is no way to force a user to pass only callback functions to your API, that meet certain requirements (i.e. accept certain arguments and have a certain return type) The core features of PEAR_Callback are: - "Static" arguments can be specified when calling the constructor. - "Dynamic" arguments can be specified when calling PEAR_Callback::execute(). - The callback definition passed to the constructor allows you to specify the number, order and type of static and dynamic arguments. - It is already the constructor that will throw a PEAR_Callback_Exception if the callback function is not callable; it is therefore impossible to create a callback that is not callable. - If the callback definition contains type specifications for the dynamic arguments, execute() will enforce these constraints. - PEAR_Callback::checkSignature() can be used to ensure that the callback function accepts certain arguments and has a certain return type before calling PEAR_Callback::execute(). - The PEAR_Callback constructor can interpret a traditional callback pseudo-type. - in-depth documentation: tutorials and API documentation - 89 phpt unit tests Cheers, Lukas