Re: Allow dropping typehints during inheritance

Hi Julien, > On 5 Feb 2015, at 12:10, Julien Pauli <jpauli@php.net> wrote: > > If we allow larger type, why doesn't such code work ? > > interface A { } > interface B extends A { } > > class C { > public function foo(A $a) { } > } > > class D extends C { > public function foo(B $a) { } // E_STRICT > } > > This is wrong IMO. Well, firstly that’s the wrong way round: inheriting classes can only *increase* the range of supported values, but you’ve done exactly the opposite. But even if you fixed your code, you’d still have an error. This ispresumably because doing anything other than simple invariance causes enormous problems related to compilation order and autoloading, as we discovered with the Return Types RFC. I think that we’d probably support full contravariance for parameters if we could. However, we could easily support contravariance in type hint existence, as that doesn’t require subclassing checks. -- Andrea Faulds http://ajf.me/