Req #52583 [Opn]: Improved casting and hinting, new magic method __cast()

Edit report at http://bugs.php.net/bug.php?id=52583&edit=1 ID: 52583 Updated by: degeberg@php.net Reported by: martin dot leucht at gmail dot com Summary: Improved casting and hinting, new magic method __cast() Status: Open Type: Feature/Change Request Package: Class/Object related Operating System: Irrelevant PHP Version: Irrelevant Block user comment: N New Comment: See: http://wiki.php.net/rfc/class_casting_to_scalar Previous Comments: ------------------------------------------------------------------------ [2010-08-11 16:30:02] martin dot leucht at gmail dot com Description: ------------ Type casting in PHP is currently limited to the builtin types. It would be very useful (IMO) if one could cast a value/variable to a class. And also type hinting could be improved by casting instead of type checking only. I suggest to solve this by introducing a new magic method for classes, called "__cast()", that accepts the value to cast as parameter. I see two possible solutions for its functionality: (1) __cast() replaces the constructor method This will force the developer to move logics from the constructor into a separate function/method (which isn't even so bad) or to copy his code (which is indeed bad). If the function returns with the boolean value "false", the default error mechanism is started saying something like "cast to XYZ not allowed". (2) __cast() acts like a static constructor The code must return the casted result itself. That means one would implement some logics to transform the given value to the needed constructor parameters and create a new instance on his own. To handle an unsupported value the method would throw an exception or an error. The negative (or let's say curious) thing about this solution is, that this cast method could also return a value of a totally different type (see example). Test script: --------------- // see patch file Expected result: ---------------- // working cast Actual result: -------------- // parse errors ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=52583&edit=1