Re: and then... (a curiosity)

[Robert A Duff <bobduff@shell01.TheWorld.com>]

Keith Thompson <kst-u@mib.org> writes:

> follow mathematical notation (in part because there is no single
> mathematical notation).  If you try to write code that will be
> understandable to someone who doesn't know the language, you'll end up
> with an overly verbose mess that can hardly be understood by someone
> who *does* know the language.
>
> If I were doing the equivalent of the above in C, whose logical "and"
> operator "&&" does do short-circuit evaluation, I probably would
> declare the two temporaries.  In Ada, it's just not necessary.

Perhaps I agree, but this discussion is (at least in part) about
language design, not just how to write good Ada (or good C or whatever).

At AdaCore, we always say "and then", never "and".  I don't like that
style (but of course I obey it, because obeying coding conventions is a
good thing in itself).

It seems to me, side effects on globals in the operands of "and" or
"and then" are just plain Bad.  The only distinction is whether the
right-hand operand makes sense when the left-hand one is False, as in
"X /= null and then X.all....".

- Bob