----- Original Message ----- From: "David Abrahams" <[EMAIL PROTECTED]>
> 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. The problems are not insurmountable though (with an "is_valid_expression"). You aren't dealing with entire language at this point, only an expression. You'd need an independent expression parser that is coupled to the symbol table. Paul Mensonides _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
