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Re: "implements" does not mean "implements"

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On 11/12/2016 5:22 AM, Sebastian wrote:
> Am 11.11.2016 um 03:05 schrieb Arne Vajhøj:
>> On 11/9/2016 7:45 PM, Stefan Ram wrote:
>>>   Just a small thought I had on the train today:
>>>
>>>   "implements" does not always mean "implements".
>>>
>>>   For example, this compiles:
>>>
>>> interface A { void m(); }
>>>
>>> abstract class C implements A { public abstract void m(); }

>> So m is in some sense present in C even though the
>> actual implementation have to be supplied by a
>> sub class.
>
> I like to say that interfaces specify behaviors of objects, not
> properties of classes. Saying that C implements A amounts to saying that
> any o that is an instance of C behaves like an A. It has nothing to do
> with what methods get implemented in C.

Behavior of objects and properties of classes should have some
relationship.

But just realized something that I think matches well
with you way of thinking.

interface A { void m(); }

abstract class C implements A { }

class Foobar extends C { public void m() { } }

actually compiles - it is not necessary to have an abstract m in C.

Arne

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Re: "implements" does not mean "implements" Arne Vajhøj <arne@vajhoej.dk> - 2016-11-10 21:05 -0500
  Re: "implements" does not mean "implements" Sebastian <nowhere@nirvana.org> - 2016-11-12 11:22 +0100
    Re: "implements" does not mean "implements" Arne Vajhøj <arne@vajhoej.dk> - 2016-11-12 08:50 -0500
      Re: "implements" does not mean "implements" Sebastian <nowhere@nirvana.org> - 2016-11-13 22:30 +0100
        Re: "implements" does not mean "implements" Arne Vajhøj <arne@vajhoej.dk> - 2016-11-14 19:48 -0500

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