Re: Interface inheritance

On Apr 20, 2004, at 10:48 AM, Ferdinand Beyer wrote:

On 20 Apr 2004 at 17:38, Stanislav Malyshev wrote:

FB>>interface A {

FB>>    public function doSomething($integer1, $integer2);

FB>>} FB>> FB>>interface B { FB>> public function doSomething(MyObject $obj); FB>>} FB>> FB>>class Impl implements A, B FB>>{

FB>>    // "Overloaded" - supports both doSomething() interfaces
FB>>    public function doSomething()
FB>>    {
FB>>        // Use var_args to distinquish the two doSomething()'s
FB>>    }

FB>>} The problem here that you can't know if Impl would actually accept MyObject or two integers as arguments. So if some method

requires object

with interface A and it's passed Impl, it cannot actually be sure it

can

use it as an A object.

Impl guarantees that by implementing interface A. What if Impl::doSomething() would accept exactly two parameters, but expects them to be arrays? IMO you cannot enforce this strictness with loose types...

This is probably a bad argument since while PHP doesn't currently allow type hinting based on whether a parameter is an array vs. a scalar, it's technically feasible and their is no good auto-casting from array to scalar or vice-versa. A better argument is expecting different types of scalars. That would be much harder with PHP's typing semantic. George