Re: Other Ada Standards (was Re: SIGada Conference)

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

Robert A Duff wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
> 
>> Just allow "with" everywhere "use" is allowed. Then "use A.B" could
>> literally imply "with A.B".
> 
> That would defeat the whole purpose of with_clauses.  The point of
> with's is that you can see a summary of the interconnections between
> compilation units all in one spot, right up front.

Should a reader see these interconnections? Couldn't we bring the famous "it
is a question of a good IDE" argument here?

> The most important aspects of a software design are: what are the
> pieces, and which pieces interact with which other pieces.  Scattering
> this information all over the place is a bad idea, IMHO.

Again, true. But it is not compilation units which interacts, but rather 
smaller objects.

> Why bother with with at all?  You might as well just say that any
> reference to a name automatically imports that name, as necessary.
> There are other languages that do something like that.

Absolutely. I think that the compilers are enough mature to go without with.
Can we go so far? [with-ing generic children is really boring] Will
implying of "with" be backward compatible?

>> So:
>> 
>> package A is
>>    package B is
>>    ...
>> end A;
>> 
>> with A.B; -- This is OK, implies with A, as usual
>> package C is
>>    with A.B; -- This is also OK
>> 
>> BTW, this would give numerous addititional possibilities:
>> 
>> package X is
>>    -- public things
>> 
>> private
>>    with Something_Implementational.Not_To_Expose;
> 
> It is indeed unfortunate that you can't have with's that apply only to
> the private part.  IMHO, the language would be better if the with's
> appeared *inside* the package, either at the start of the visible part,
> or the start of the private part, or the start of the body.  But I want
> them together, up front (for each of these parts) -- not scattered all
> over.

To enforce this we would need to formally define "start-of-a-part" in RM.
IMO it is easier to allow it everwhere with a stylistic note that it is
better to place it as early as possible in the text.

> By the way, I think there's an AI allowing with's to apply to the
> private part.  Something like "with private X" or "private with X".
> It still has to go outside, *before* the text of the package spec,
> which is unfortunate.  My suggestion of putting the with's inside is way
> too big a change to consider seriously.

-- 
Regards,
Dmitry A. Kazakov
www.dmitry-kazakov.de