Re: Using child classes/interfaces as desired type hints

On Thu, October 7, 2010 12:56 am, Nathan Nobbe wrote: > <?php > abstract class AbstractServer {} > class ConcreteServer extends AbstractServer {} > > abstract class AbstractClient { > abstract function doStuff(AbstractServer $o); > } > > class ConcreteClient extends AbstractClient { > function doStuff(ConcreteServer $o) {} > } > ?> > > This results in a fatal > Fatal error: Declaration of ConcreteClient::doStuff() must be > compatible > with that of AbstractClient::doStuff() in > /Users/quickshiftin/gitRepos/timberline/php-api-v15-client/testOverride.php > on line 11 > > I was reading a few posts from way back when > > http://marc.info/?t=107774904800001&r=1&w=2 > > yet still find myself wondering. I think it can be said here that if > there's a contract defined by AbstractClient::doStuff, that same > contract is > honored by ConcreteClient::doStuff. I also think changing the > language to > support this notion wouldn't raise BC issues for the most part (at > all?) > since at the moment you're forced to move to the lowest common > denominator > in the tree, in this case > > class ConcreteClient extends AbstractClient { > function doStuff(AbstractServer $o) {} > } > > your feedback appreciated, I can see why you think it "should" work, but have you considered all the possible combinations of children/parent abstract/concrete classes, and what happens when you do: class QuickMixClient extends ConcreteClient { function doStuff(AbstractServer $o) {} } class QuickMixServer extends AbstractServer { } $quickie = new QuickMixServer; $client = new QuickMixCilent; $client->doStuff($quickie); Kosher? Or not? It's kosher for the QuickMix doStuff, but does not satisfy the ConcreteServer requirement of ConcreteClient. So does PHP need to examine every method on every class, and then complain at compile time?... That sounds painful to me... . . . -- brain cancer update: http://richardlynch.blogspot.com/search/label/brain%20tumor Donate: https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=FS9NLTNEEKWBE