On Tue, May 12, 2009 at 9:43 AM, Dmitry Stogov <dmi...@zend.com> wrote: >> Apologies, I'm not familiar with run-time inheritence in PHP. My >> understanding was that when a classes source code is compiled, its >> parent classes must be known. When is this not the case? > > The parent class may be defined in other file that is loaded at runtime > using include() statement. It's very usual case. So the PHP first loads the > include file and then declares child class at runtime.
>> Must it be known for the class' first instantiation? > > Of course. :) On Tue, May 12, 2009 at 7:25 AM, Dmitry Stogov <dmi...@zend.com> wrote: > The real things is even worse as during compilation of a class it's parent > class doesn't have to be known. So construction of VMTs becomes a bit > problematic. BTW we could think in this way... OK, so I dont understand this exactly. Is it correct to say that if a class uses inheritance its compilation will be deferred until its first instantiation? Or is it compiled when it is seen, and its parent backpatched in later. When is later? But I think its fair to say that it has static inheritance - that is, its full inheritance chain is known before it can be instantiated, and it can never be changed after that. >> In the worst case, it _might_ be cheaper to build it at instantiation >> time, but I would have to look up how expensive that is in a more >> static language to be sure. Certainly, it is currently so expensive >> that almost anything else would be better (including the OP's patch). > > I don't see how run-time VMT contraction may help, because calls to virtual > method must know VMT offset at compile-time. Right. Construction is fine. Their use is not. I don't know what I was thinking. So it looks like the best way forwards is still the OP's patch? Thanks, Paul -- Paul Biggar paul.big...@gmail.com -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
