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From: Neil Madden on 23 Nov 2009 06:41
tom.rmadilo wrote:
> On Nov 22, 9:55 am, Neil Madden <n...(a)cs.nott.ac.uk> wrote:
>> tom.rmadilo wrote:
>>> On Nov 21, 4:25 am, Neil Madden <n...(a)cs.nott.ac.uk> wrote:
>>> ... (see previous post)
>>> All I can say is that you are mixing up two different points that I
>>> was trying to make.
>>> I am not saying that subtyping cannot be used to represent subtypes or
>>> "kind of" relationships. Never even got close to that.
>>> My point is simple: subtyping breaks the definition of a type/class/
>>> interface over many different files, Java is a good example regardless
>>> of extends or implements. Both are top-down and fixed. They require
>>> prior understanding of the similarities and relationships (the model)
>>> before you can create the type/class/interface hierarchy. Changes are
>>> difficult to introduce. The subtyping is a language feature and
>>> represents a different style of programming.
>> This is incorrect. There is a world of difference between the keywords
>> "implements" and "extends" in Java. Firstly, subtyping -- either as a
>> concept, or as realised in Java -- does not require you to split your
>> implementation over several files, or over several classes. Indeed,
>> subtyping says nothing about implementation whatsoever.
>
> Oh, my! The base class is in one file, the derived class is in a
> second file! Is this such a difficult thing go understand?

Yes, because it is wrong. Nothing in Java or other languages with
subtyping says that they have to be in different files. If you want to
do public subtyping, then the interface and the sub-type implementations
have to be in separate files, but that is just one case.

[...]

It's clear from this conversation that you are still conflating
subtyping with inheritance, and I cannot think of a more straightforward
way of explaining it, so there is little point continuing. Besides, it
seems clear also that you have retracted your initial claim that
subtyping and class hierarchies are a bad idea.

-- Neil
From: Neil Madden on 24 Nov 2009 06:19
tom.rmadilo wrote:
[...]
>> It's clear from this conversation that you are still conflating
>> subtyping with inheritance, and I cannot think of a more straightforward
>> way of explaining it, so there is little point continuing. Besides, it
>> seems clear also that you have retracted your initial claim that
>> subtyping and class hierarchies are a bad idea.
>
> Again, you persist in this nonsense about what I don't understand. I'm
> not trying to distinguish subtyping from inheritance.
>
> I also never retracted any statement about subtyping and
> hierarchies...how could I, according to you I don't even understand
> what subtyping is.
>
> It is amazing how you take one statement and transform it into another
> using different words and claim that I used those words with your
> selected meaning.
>
> What is the purpose of doing that? I understand it is always possible
> to misunderstand other people because you don't catch the meaning of
> the words they have chosen, but when you intentionally put your own
> words in someone elses' mouth something else is going on.

I'm sorry if you feel that I have misrepresented you. Perhaps you would
like to take this opportunity to stately clearly for the record
precisely what claims you are and are not making?

-- Neil
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