Allow arbitrary expressions when using instanceof operator

Good morning, internals! I would like to present to you an idea that I have for a syntax improvement for PHP. The basic idea is to allow arbitrary expressions when using the instanceof operator. Currently, the second operand can only be a constant reference or a string: $foo instanceof stdClass; What I want to implement is the ability to allow arbitrary expressions on the second operand, so instead of having to write something like this: $className = 'stdClass'; $foo instanceof $className; We could write something like this: $foo instanceof ($bar->getClassName()); I've been working with Nikita Nefedov on this improvement, and we managed to reach a very simple way to implement it, and it looks pretty good so far. Currently, I don't have a VCS account, and eventually I want to open a formal RFC for this, but I first wanted to discuss this with you guys to see the impressions on it and suggestions as well. Regarding BC breaks, there would be none from what I can see so far - hopefully someone more experienced will be able to point my any. So, what do you think? Cheers! Daniel Ribeiro http://danielribeiro.org