Preprocessor keyword #echo is missing

[Martin Sebor]

Gabriel Dos Reis wrote:
> Martin Sebor <sebor@roguewave.com> writes:
> 
...
> Hi Martin,
> 
>  As you know, I (and Joddy and Robert) reported on that paper at the
> last Santa Cruz meeting.  The declaration form proposed in the paper
> doesn't integrate into the language general rules.  Robert and I
> agreed on pursing the idea from expression point of view.  But there
> remains some corner cases to work out.  
> 
> At any rate I would not support a preprocessor extension to implement
> that -- for reasons given the the refrenced paper.

Yes, I think recall your involvement with the proposal. That's
why I would have expected you to be interested in a compile-time
context-sensitive I/O facility like #echo (the name doesn't matter,
it could be #pragma __echo). Are you saying you don't find the
feature useful in general or just that it doesn't belong in the
preprocessor (I certainly agree with that unless it's limited
to what #error does).

Some time ago, I read a paper on metaprogramming in various
languages. The paper bemoaned the lack of a compile-time I/O
(or more precisely, just O, there's no need for input) facility
in C++. Let me try to find it -- I suspect it might present a
more compelling case for the feature than I can :)

Martin