Re: A simple ADA puzzle (I haven't the answer)

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

On Mon, 21 Jun 2004 03:30:32 GMT, Hyman Rosen <hyrosen@mail.com>
wrote:

>Dmitry A. Kazakov wrote:
>> What's the gain of limiting scope here? A relief for lazy
>> programmers, who do not want to create extra *.h files?
>
>The same gain as any limitation of scope - localizing things
>to the narrowest region where they are needed. It is no less
>sensible than Ada's declare statement. I often write tiny
>classes whose job is nothing more than invoking a cleanup
>function on an object in its destructor. I put them right next
>to the object they will be handling.

I usually put helper classes in the class of the object, but it is a
matter of taste.

>> Limiting scope is useful, but it should be made consistently.
>> Clearly a nested thing should see everything from its scope.
>
>C and C++ do not choose to allow closures because of difficulties
>with function pointers that result.

Same fault as in Ada. There should be routine types, which in most
cases would eliminate any need in pointers.

>So it is clear that access to
>local variables will never be permitted.

So it is inconsistent.

>The question is then
>whether to also forbid a useful thing because of misguided efforts
>to impose a useless philosophy.

That's another philosophy, the C++'s one: quick and dirty, or rather
"let's first make it dirty, maybe it happens to be quick".

>Fortunately the answer was "no".

One cannot correct one error by making another.

>> Talking about uneducated programmers how would you explain one of them
>> what and when will be visible? Ada's choice was to give a clear,
>> though unpleasant answer, rather than vague "yes, but".
>
>As I have said, it's extremely simple. Automatic variables are invisible.

Huh, how is it better than Ada's limitation on tagged types?

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