Re: Ada OO Mechanism

[Samuel Mize <smize@imagin.net>]

Chris <Chris@newsguy.com> wrote:
> In article <7if7oj$bee@news1.newsguy.com>, Samuel says...
>>
>>I do know that this distinction is extremely useful in a mixed-method
>>environment, e.g., object-oriented and procedural elements working
>>together.
>>
> 
> I don't think it leads to clear design when one part of the
> program is done in OO ways, while another part is not.
> 
> one either uses all OO, or all procedural.
> 
> don't you agree?

Nope.

But then I've worked on very large systems, with multiple fairly
independent subsystems interacting inside the language.  For
instance, we had an object-oriented design which needed object
persistence -- that is, many objects stored their attributes
between executions of the system, re-reading their current state
at start-up.  The repository for these objects was really just a
simple data base in this design, and when we tried to switch it to
an object-oriented implementation it was much less clear, less
maintainable, and slower.

Another example would be a process control system that interacts with
things like inventory control and materials routing.  I could easily
imagine that you would want to implement safety-critical control
loops in a very controlled procedural fashion -- in this area, you
are inherently thinking about actions more than objects anyway.
Then you could interface this to an object-oriented representation
of the physical objects being manipulated.

In short, I've worked in mixed-method environments, and as long as
you clearly define where each method is going to be used, it's quite
useful and powerful.

At SOME point you stop doing OO work and switch to a procedural
model, at least when implementing a class's method bodies.  Unless,
of course, you're coding in something like Smalltalk that is
object-oriented all the way down to integers (I understand).  I
don't think you'll sell the argument that this is necessary, or
even clearer to most people than procedurally-coded methods.

Best,
Sam Mize

-- 
Samuel Mize -- smize@imagin.net (home email) -- Team Ada
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