Re: Conditional compilation in Ada?

[Jeffrey Carter <spam@spam.com>]

Steve wrote:

> Using variant records means explicitly checking for the variant type and
> taking different action based on the variant.  Creating a new variation of
> the record means modifying the original record (modifying proven code is
> never a good thing when it is easily avoided) and chasing each part of the
> code that takes different action based on the variants.

Since the compiler points out any place where you've forgotten, this is 
hardly a problem; indeed, I would claim that it's an advantage over OOP, 
where forgetting to redefine an operation is ignored by the compiler, 
and you get the wrong action instead.

In a well designed system, all the code dealing with the variant record 
and its variants will be together, so there's no "chasing each part of 
the code".

Another advantage of using a variant record is that what happens is 
explicit in the code, not hidden is some package that is not mentioned 
in a context clause.

> Using objects means deriving a new object and overloading specific
> operations for that object.  The base object isn't touched.

And operations that are mistakenly not overridden become run-time errors.

> Also: If the object is declared statically, the dispatching may happen
> statically.

This is true, but it seems that the nature of OP's problem would prevent 
this.

-- 
Jeff Carter
"I fart in your general direction."
Monty Python & the Holy Grail
05