[boost] [proprocessor] PP challenge!

From: Eric Niebler (eric_at_[hidden])
Date: 2006-11-04 16:24:04

I have a preprocessing task that exceeds my limited abilities. If any PP 
gurus want to step in and prevent me from hurting myself further, I 
would be very grateful.

My problem is this: I want to mpl::and_ together a bunch of predicates. 
mpl::and_ has a limit of 4 arguments. So this is wrong:

   mpl::and_< pred1, pred2, pred3, pred4, pred5 >

but this is ok:

   mpl::and_< pred1, pred2, pred3, mpl::and_< pred4, pred5 > >

The challenge, should you choose to accept it, is to write some PP magic 
that, given a MAKE_PREDICATE(z, n, data) macro and a max arity (which is 
greater than 4!), generates a properly nested mpl::and_-ing of the 
predicates.

Any takers?

-- 
Eric Niebler
Boost Consulting
www.boost-consulting.com