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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Comparison : Ada and UML =?utf-8?Q?=28comparison=E2=80=A6?=
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Date: Wed, 10 Nov 2010 21:31:06 +0000
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Date: 2010-11-10T21:31:06+00:00
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Matteo Bordin <matteo.bordin@gmail.com> writes:

> On Nov 9, 9:02 pm, Simon Wright <si...@pushface.org> wrote:
>> Matteo Bordin <matteo.bor...@gmail.com> writes:
>> > a UML class needs to be instantiated to have a run-time executable
>> > semantics
>>
>> I don't understand this?
>
> What I meant to say is that a UML class is not an instance. This was
> related to the discussion about HOOD and the problem of mapping the
> notion of HOOD object to a UML element. Mapping it to a class is
> controversial because the two elements are really different: a UML
> class needs to be instantiated, a HOOD object is already a "runnable"
> element.

So a UML class is something similar to an Ada type, in that you need to
create an object of the type in order for anything to happen. Not sure
that 'instantiate' is the right word for this process, maybe it has this
specific meaning in the UML world?

Would a HOOD model of an aircraft with 4 engines have one HOOD object
for each engine?

>> There has to be some sort of profile (both in allowable UML constructs
>> and what they mean in terms of program execution). "If you model like
>> _this_ and generate code using _our generator_, the result will work
>> like _that_".
>
> Sure, but this way you may risk to model your application based on a
> precise code generation strategy, possibly loosing portability and
> platform-independence of models.

Even a PIM has to have pretty precise semantics. I suppose I should have
said, "If you model like _this_ and generate code using _our
*standard-conformng* generator_, the result will work like _that_".

If that's not so, the platform-independence isn't worth much.