Req #46705 [Com]: Impossible to implement compatible interfaces

Edit report at https://bugs.php.net/bug.php?id=46705&edit=1 ID: 46705 Comment by: smith at pooteeweet dot org Reported by: wrzasq at gmail dot com Summary: Impossible to implement compatible interfaces Status: Open Type: Feature/Change Request Package: Scripting Engine problem Operating System: Debian GNU/Linux PHP Version: 5.2.6 Block user comment: N Private report: N New Comment: Note its also not possible to redefine while adding new optional parameters <?php interface fooI { function ding(); } interface barI extends fooI { function ding($dong = null); } class bar implements barI { public function ding($dong = null) { echo 'woho: '.$dong."\n"; } } $bar = new bar; $bar->ding('yeah!'); Previous Comments: ------------------------------------------------------------------------ [2011-03-22 23:33:03] clicky at erebot dot net I think this use case, the one bug #43200 and the one below are all valid: <?php interface A { public function foo(); } interface B extends A { public function foo(); } class C implements B { public function foo(){} } ?> The case above may seem odd (there's really no point in redefining the exact same interface), but I have a simple use case where this may prove handy. I'm currently writing some code for a little project which is meant to teach some middle to advanced topics of PHP. The code is self-documented (using doxygen) and uses some interface from SPL (Countable). That interface is used several times in different files and I'd like to document the count() method only once (if possible, at the interface level -- then using doxygen's ability to copy/paste the doc from parent classes/interfaces into the current class). I thought I could just define my own interface (Project_Countable), extending from SPL's Countable, "overriding" the method's signature (only so doxygen can pick up the method's declaration -- the prototype for the method was actually left unchanged) and then define a class that implements Project_Countable. So in my case, A = SPL's Countable interface and B = Project_Countable. However, this pattern can't be used as it results in the same error others noted here and in bug #43200. I can't simply avoid Project_Countable extending from Countable, because then I would lose count()'s "magic" by doing so. ------------------------------------------------------------------------ [2008-11-28 07:57:42] wrzasq at gmail dot com Description: ------------ It is impossible to implement multiple interfaces that declares same methods. I saw bug #43200 but this is a bit different case and I think in this situation it shoud be allowed - those interfaces requires methods with same signature (also to prevent further problems - optional parameters should also be allowed to match signatures): Reproduce code: --------------- <?php interface A { public function foo(); } interface B { public function foo(); } class C implements A, B { public function foo(){} } Expected result: ---------------- nothing, but working Actual result: -------------- Fatal error: Can't inherit abstract function B::foo() (previously declared abstract in A) in /home/wrzasq/Desktop/Www/engine/- on line 16 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=46705&edit=1