Re: Package's private parts and protected types

[Stephen Leake <stephen_leake@stephe-leake.org>]

Robert A Duff <bobduff@shell01.TheWorld.com> writes:

> Adam Beneschan <adam@irvine.com> writes:
>
>>...And that
>> issue exists with GNAT also---you delete some files from your
>> directory with a wildcard, somehow foo.adb accidentally gets deleted
>> along with them, and the compiler still thinks your program is OK.
>
> Seems unlikely.

Which means it will be very hard/confusing to debug when it does
happen, since you will not be familiar with the problem. So it is
important for the tool to handle the unlikely situations nicely.

> Here's a similar issue: One reasonable design pattern is to have
> a body that contains a type extension, which registers itself
> into some global data structure.  All calls to this thing
> are indirect (via the parent's 'Class).  Nobody needs visibility
> on this thing, so its spec is completely empty, except for
> the obligatory pragma Elaborate_Body.  Unfortunately, if you
> forget to 'with' it, it will be silently ignored.

And if you do 'with' it, GNAT will complain that it's unnecessary, so
you have to put a pragma Warnings (off) on it. QtAda does this for
some stuff; it's annoying.

I prefer to handle that case by making the registration function
visible in the package spec, rather than calling it in the package
body execution part. Then the main program has to call it, and no
compiler warnings are generated.

-- 
-- Stephe