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Re: Object orientation question

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On 10/28/2014 8:29 AM, Eric Sosman wrote:
> On 10/28/2014 5:45 AM, Andreas Leitgeb wrote:
>> Robert Klemme <shortcutter@googlemail.com> wrote:
>>> On 27.10.2014 21:51, Eric Sosman wrote:
>>>>       Clearly, the generated code is the same: AdditionInterface
>>>> extends
>>>> BaseInterface, therefore any class implementing AdditionInterface also
>>>> necessarily implements BaseInterface.  If the class fails to provide a
>>>> method specified by BaseInterface, the code won't compile.  So the
>>>> question is purely about readability and style.
>>> This is not fully correct: if you check with reflection you will see
>>> that there is a difference in what Class.getInterfaces() returns.
>>
>> You don't even need reflection to notice a difference:
>>
>> interface A { ... }               |  interface A { ... }
>> interface B { ... }               |  interface B extends A { ... }
>> class C implements A,B { ... }    |  class C implements B { ... }
>> ...                               |  ...
>>     B foo = new C();               |     B foo = new C();
>>     A bar = foo;  // barf!         |     A bar = foo; // ok
>>
>> Instead of the second assignment you could have a call to a
>> method that takes an A and gets passed B-typed reference foo.
>
>      My Java compiler (Oracle's 1.8.0_20 on 64-bit Windows 7)
> doesn't "barf" as you report.  Has something changed?  Are you
> using a different javac?  Here's the code; I've fleshed out
> the ellipses and changed one name:
>[...]

     Ah, but I mis-read your post! On the left you have A and B as
completely independent interfaces, whereas on the right one is a
sub-interface of the other.  The O.P. wrote (emphasis mine)

	We have an interface called BaseIface and then we have a
	BaseImpl. Then we have AddtionInterface and AdditionImpl.
	*AdditionInterface is a BaseInterface.*

... so your left-hand case is different from the situation he
asked about, and which I was addressing.  Sorry for the confusion.


-- 
esosman@comcast-dot-net.invalid

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Object orientation question mike <mikaelpetterson@hotmail.com> - 2014-10-27 13:26 -0700
  Re: Object orientation question Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-10-27 16:51 -0400
    Re: Object orientation question Robert Klemme <shortcutter@googlemail.com> - 2014-10-27 23:51 +0100
      Re: Object orientation question Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-10-28 09:45 +0000
        Re: Object orientation question Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-10-28 08:29 -0400
          Re: Object orientation question Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-10-28 08:33 -0400
            Re: Object orientation question Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-10-28 16:26 +0000
        Re: Object orientation question Robert Klemme <shortcutter@googlemail.com> - 2014-10-29 08:35 +0100
          Re: Object orientation question Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-10-30 00:32 +0000

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