From: vesa_karvonen (vesa_karvonen_at_[hidden])
Date: 2002-03-08 10:11:50
--- In boost_at_y..., "David Abrahams" <david.abrahams_at_r...> wrote:
> From: "vesa_karvonen" <vesa_karvonen_at_h...>
> > hmm... I've tried to use the same one character names for every
> > macro parameter used for the same purpose in the library, but
> > there are still many exceptions to the rules. I'll try to fix
> > those exceptions and add a separate page that explicitly explains
> > the naming of parameters.
> I'm sorry; I don't see how that's relevant.
Don't worry about it :). I'm just trying to find ways to minimize the
amount of documentation needed while making the documentation
> My point was that the user needs to choose something to be passed
> for R when she invokes BOOST_PP_LIST_FOR_EACH_I(). In general,
> almost anything will do.
BOOST_PP_LIST_FOR_EACH_I(F,P,L) takes 3 parameters none of which is
named R. This is why I explained the difference between the generated
R and D parameters and the user specified P parameter.
The root cause for all this confusion is really the design of the C
preprocessor which does not allow recursion. The technique of passing
around explicit recursion depths (R and D parameters) is a technique
for overcoming this limitation of the C preprocessor.
> > > You could look at boost/python/converter/from_python_data.hpp
> > > for what I ended up with.
> > I think that it should be possible to achieve the same effect
> > using only MPL, which might be preferable.
> Trust me, the PP library was a last resort. It was too slow with
> various EDG compilers when I just used template metaprogramming.
That is quite interesting. Are you really saying that iteration using
BOOST_PP_LIST_FOR_EACH_I() in this case is faster than when using
boost::mpl::accumulate<>? The template metaprogramming version
potentially does the iteration many more times than the pp
metaprogramming version, but still it sounds quite odd. I suppose
that with precompiled headers, the pp metaprogramming version should
clearly be faster, because the iteration is then "unrolled".
Boost list run by bdawes at acm.org, gregod at cs.rpi.edu, cpdaniel at pacbell.net, john at johnmaddock.co.uk