Re: Overloading procedures with Float and Long_Float types

["David C. Hoos" <david.c.hoos.sr@ada95.com>]

----- Original Message ----- 
From: "Luke Guest" <lguest@bubball.com>
Newsgroups: comp.lang.ada
To: <comp.lang.ada@ada-france.org>
Sent: Monday, March 08, 2004 8:03 AM
Subject: Re: Overloading procedures with Float and Long_Float types


> > What is the result of this procedure?  There are no out or "in out"
> > parameters.  I would expect something like this to either be a
> 
> It doesn't need them, this is OpenGL!
> 
> Translate calls an imported glTranslate[fd] procedure depending on the
> parameter types.
>
Ah, you're calling a function with no return type which modifies a
hidden matrix, in place -- not a very good software design, IMHO.

But, if you're binding to software with a poor design, I guess you
have no choice,
 
> > As a matter of good practice, I would not use the type "Float",
> > but would explicitly make the two subtypes Short_Float and
> > Long_Float.
> 
> Would this allow the compiler to determine whichprocedure to call based
> purely on numbers?
>
No, it wouldn't -- it would just give a further measure of
compiler-independence -- a good thing.

Incidentally, in your example, you're not calling "purely with numbers."
you're calling with character representations of numbers which have, in Ada
the type Universal_Real.  You need to call with values of the type with
which you wish to select the overloaded procedure to be called.

To do this, my choice would be to use a qualified expression (RM 4.7),
rather than use a type conversion as others have suggested.

> Translate(1.0, 0.0, 0.0); -- Is this Short_Float or Long_Float?
>
Neitheer -- it's Universal_Real
 
> Luke.
> 
> 
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