From: Greg Colvin (gcolvin_at_[hidden])
Date: 2000-11-09 13:23:51
From: Beman Dawes <beman_at_[hidden]>
> John Maddock wrote:
>
> >Beman,
> >
> >>Perhaps I should just work on a core proposal for a new language
> >>feature. All of the macro uses we are talking about are needed to get
> >>__FILE__ and __LINE__. How about two new special symbols:
> >>
> >>namespace boost {
> >> static_assert( bool exp, const char * file=__FILE_AT_USE,
> >> int line=__LINE_AT_USE );
> >>}
> >>
> >>The compiler is required to replace these with the appropriate value at
> >the
> >>point of a call to static_assert(), rather than at point of declaration.
> >
> >If this were going forward as part of the standard I would say yes call
> in
> >"static_assert" and place it <cassert>, either as a regular macro, or as
> a
> >core language extention (depending how the vendor sees it).
> >
> >However, there is a problem with your approach wrt boost: how does the
> >static_assert function you've defined above, convert the bool parameter
> to
> >a static assertion (as an integral constant expression)?
>
> I don't know without language support. It keeps coming back to that; there
> needs to be better language support for diagnostic tools.
>
> __FILE_AT_USE and __LINE_AT_USE would allow some better user written tools
> like various improved runtime asserts, so they wouldn't be be totally
> useless. I'm just trying to provoke thought, not actually present a
> finished solution.
I recall that my proposal for a similar __WHERE__ macro was not well received.
Another related problem is that using the assert macro in inline code can
easily lead to violations of the One Definition Rule.