[boost] Re: Re: boost :: mpl timeline? (Macros a necessary evil,#redefand non-lazy evaluation, BOOST_PP_INC etc)

From: Dylan Cuthbert (dylan_at_[hidden])
Date: 2002-06-26 05:52:27

So where do we sign the petition?  ;-)

What C++ compiler are you using by the way?

---------------------------------
Q-Games, Dylan Cuthbert.
http://www.q-games.com

"Paul Mensonides" <pmenso57_at_[hidden]> wrote in message
news:000701c21cd1$da9510a0$7772e50c_at_c161550a...
> > I see what you mean - it would probably be more trivial to implement
than my
> > escaped #cmds method. (and hence easier to persuade "those-that-be").
> >
> > Macros *are* evil, yet sometimes there is just is no solution but to use
> > them, so when you are forced to use them it would be nice if their
feature
> > set was just that little more complete.  They (cpp steering committee?)
took
> > far too long to even implement the "new" __VA_ARGS__ feature, a feature
I
> > have been using in gcc since around 1993.
>
> Macros are 'basically good' just misused. <-- :)  Some things C++ proper
cannot
> do without comprising the whole system and only supporting special cases.
>
> Unfortunately again, I can't use __VA_ARGS__ in C++.  Hopefully, *they*
will add
> this in C++0x, but with the preprocessor, it's anybody's guess.
>
> It is possible with __VA_ARGS_ (in combination with a little
> template-metaprogramming) to implement overloaded classes.  I have already
> implemented this for things like Loki's Typelist.  Right now, (without
> __VA_ARGS__) we have three possibilities:
>
> TYPELIST_3(int, int, int)
>
> TYPELIST((int, int, int))
>
> Variadic macros could reduce the last to:
>
> TYPELIST(int, int, int)
>
> Of course, we have the C++ alternative:
>
> typelist<class A, class B = null_t, class C = null_t> // etc.
>
> But then you have to bother with checking against null_t, etc..
>
> > To bring it back to the boost newsgroup :-) imagine how much simpler the
> > BOOST_PP_INC/DEC set of macros would be eh?
>
> Not simpler, but a *lot* shorter. :)  More importantly, how much *faster*
> arithmetic would be on some compilers (EDG anyone?).
>
> Paul Mensonides
>
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