caller function?

Hi! Anyone here working on a caller() function? I spent a couple hours last night looking through the zend code, and I think may be able to do it, but if someone more experianced is working on it then I'll leave it alone. If no one is working on it, could someone give me a hint or two on where to start, or how it would be implemented _correctly_? Also, any thoughts on some type checking syntax? ie. function hello((string)$name) { print $name; } if $name isn't a string php would stop and give a fatal error. or function mytest((MyDisplayObj)$displayobj) { print $displayobj->status; } I can see this making classes and reusable code _much_ easier to use and less error prone. Tom