Re: Ada95 OOP Questions

[cosc19z5@Bayou.UH.EDU (Spasmo)]

Ken Garlington (garlingtonke@lmtas.lmco.com) wrote:
: Spasmo wrote:

[Snip]

: Depends on what you're abstrating. If you don't want an abstract data type,
: but you want a generic abstract data object, why not do this:

:   generic
:   package Person is

:     procedure Walk;
:     procedure Talk;
:     procedure Eat;

:   private

:     type Person_Type is -- as before
:     Object : Person_Type;

:   end Person;

: Translating your C++ code:

:    package P is new Person;  -- Person p;
:    P.Walk;                   -- p.walk();
:    P.Talk;                   -- p.talk();
:    P.Eat;                    -- p.eat();

: Note, however, that there are things you can't do with a GADO (like
: make an array of Persons) that you can do with an ADT.

Yeah that's something I fiddled with initially but realized
that it just didn't work with arrays and the like.  Sure I
could arbitrarily create as many instances of the above package
as I liked (via new packages) but I couldn't use arrays, linked
lists of them, etc...



: If your complaint is that you like p.eat() better than eat(p), on the
: other hand, then I don't see this as an abstraction difference - just
: a syntax difference.

Right it was the syntax that got to me -- and I came to grips
with that :).


: Just out of curiousity, if Person is declared in the C++ equivalent of
: a package (and I forget the nomenclature -- space?), what does your C++
: code look like?

Well when I used C++, things like namespaces, RTTI (standardized?)
and even exception handling weren't universally implemented so
in all reality these classes were taking up the global name space.



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Spasmo
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