Re: Constructors/Destructors in Ada95

[Ray Blaak <blaak@infomatch.com>]

Francois Godme <fgodme@bigfoot.com> writes:

> I. Non-primitive procedures used as constructors of limited instances: As
> limited instances can't be initialized with record aggregates, it is possible
> to write code which forgets to initialize all record fields.

Forgetting to initialize a field is equivalent to using a default constructor,
no? In that case the Initialize routine can cover it.

If not field is not a tagged type, either a default component assignment can
cover it, or if limited, the compiler should flag an error that the item is not
created.

I do grant you, however, that C++'s constructors are nice for forcing an item
to be created in only valid ways.

> II.The Adjust procedure: Efficiency concerns may be raised against the
> sequence: Finalize (Target); shallow copy Source into Target; Adjust
> (Target);.

I really would like to be able to do:

  procedure ":="(target : in out T; source : in T);

so as to have complete control over what is happening. I vaguely recall some
rationale from the Ada 9X discussions for why user-defined assignment per se
was not incorporated. Does anyone remember?

> III. The Finalize procedure:
> The programmers are responsible in the Finalize procedure to call last the
> immediate super-class Finalize procedure. As the notion of immediate
> super-class does not exist in the language, it is not possible to write code
> that will always call the Finalize procedure of the immediate super-class.

Not just in Ada. This bug has bitten me in C++ too often during redesign
times. Java's "super" and Delphi's "inherited" keywords neatly make this issue
go away.

Anyone know of a reason why "super" would not be a good idea for Ada 0X?

-- 
Cheers,                                        The Rhythm is around me,
                                               The Rhythm has control.
Ray Blaak                                      The Rhythm is inside me,
blaak@infomatch.com                            The Rhythm has my soul.