Re: Ada OO

[Graham Hughes <graham.hughes@resnet.ucsb.edu>]

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bobduff@world.std.com (Robert A Duff) writes:

>The syntax is similar, but other than that, they are not similar.
>CLOS is vastly more powerful, and more complicated, than Ada
>(or any other OO language I've ever used).

I can definitely agree with that; never seen :around, :before, or :after
anywhere else.  Even Smalltalk doesn't allow the extreme hair you can
see with metaclasses.

>                        Dispatching-on-function-result is something
>C++ doesn't have.  Also, Ada has class-wide parameters -- a procedure
>with class-wide parameters is not dispatching (unless some other
>parameter makes it so).

This is probably because I learned OO on my own, but what exactly is
`dispatching-on-function-result', and class-wide parameters?  Does the
last refer to the way you specify parameters when instantiating a
generic?

>Well, sort of.  But in CLOS the methods are scattered all over,
>whereever the programmer chooses.  In Ada, they're collected together in
>a single package.

Which is quite handy some times, I've noticed.

>>Finally, re: the abstract; is it needed in the package body, or can it
>>be ommitted?

>Umm.  Not sure what you mean.  Can you give an example?

Basically, I was kind of confused whether you needed to mention an
abstract method/subprogram in the package body, or whether you could
just assume everybody knows what you mean.  Fortunately, the latter is
true :).
- -- 
    Graham Hughes (graham.hughes@resnet.ucsb.edu)
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