Re: [boost] Re: is_convertible corner case

From: David Abrahams (dave_at_[hidden])
Date: 2003-01-24 18:36:10

"Paul Mensonides" <pmenso57_at_[hidden]> writes:

> I do, however, agree that we need more support from the language for
> generic programming and some type of standardized API into the
> compiler's type system.  And I definitely think that "undefined
> behavior" is unreasonable when the situation is easily diagnosable
> and not platform specific.

I tend to agree on a "moral/aesthetic" level, but on a practical level
we have to tread carefully.  The question, "can we just have an
operator which produces a compile-time constant value saying whether
its operand is a valid expression?" has come up a few times in the
committee.  Each time, the implementors looked at their codebases and
said "oooh, that's really hard to do."  I think the short form of the
reason is that C++ compilers generally don't have the ability to
recover from errors reliably.  That may explain why your 2nd, 3rd,
4th... diagnostic messages tend to be useless gibberish ;-)

So, I'd like to push for something like that but practically speaking
I'm not sure how to get there.

-- 
                       David Abrahams
   dave_at_[hidden] * http://www.boost-consulting.com
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