Re: [boost] [preprocessor metaprogramming] tools

Subject: Re: [boost] [preprocessor metaprogramming] tools
From: Hartmut Kaiser (hartmut.kaiser_at_[hidden])
Date: 2012-07-30 09:19:44

> >>>>> I wanted to share with you something I've found very useful for
> >>>>> tracing/debugging macro metaprograms: the Eclipse CDT IDE has a
> >>>>> "macro stepper" that allows you to step through the expansion of a
> >>>>> macro step-by-step from the initial invocation to the final
> >>>>> expansion. (This feature can be accessed by using the "Explore
> >>>>> Macro Expansion" context menu item on a macro invocation.)
> >>>>
> >>>> This seems very nice, and probably can help especially when
> >>>> debugging deferred expressions. However, will it show when a macro
> >>>> is painted blue? That is really important to knowing why it didn't
> expand.
> >>>
> >>> Unfortunately it does not show that. That would be a nice addition.
> >>
> >> Wouldn't it be possible to build something really useful on top of
> >> the Wave library?
> >
> > The Wave tool ($BOOST_ROOT/tools/wave) allows generating traces for
> > the expansion of macros. See the docs for it's done
> >
> (http://www.boost.org/doc/libs/1_50_0/libs/wave/doc/tracing_facility.html)
> .
> > Macro tracing in Wave does not show when a macro has been painted
> > blue, however it allows following in detail what happens during the
> > expansion of a particular macro. The information about a macro being
> > painted is available and could be added to the tracing facility easily.
> 
> I have always found the Wave trace facility to be amazingly helpful in
> discovering how a macro should be expanded correctly. Just want to say
> thanks for this ability. Any further information that can be shown when
> expanding a macro, perhaps as a Wave trace option, is always welcome and
> appreciated by this programmer. Maybe something like a --verbose option.

Well, thinking about it... The trace already (implicitly) has the
information about a macro name being blue painted. The rescanning [...]
output gives you the scope for which the macro under expansion is not
available for further expansion (e.g. it is marked blue).

Regards Hartmut
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