Re: [Boost-users] [bcp] [shared_ptr] [wave] Extracting subset of boostforshared_ptr - 3.2MB?

From: David Abrahams (dave_at_[hidden])
Date: 2006-02-18 13:01:51

"John Maddock" <john_at_[hidden]> writes:

>> Unfortunately bcp isn't smart enough to not look into optional
>> dependencies that are guarded by #ifdef. In this particular case it
>> follows the dependency to detail/quick_allocator.hpp, which in turn
>> brings in the type_traits and mpl libraries. But quick_allocator.hpp
>> is only used if you #define BOOST_SP_USE_QUICK_ALLOCATOR.
>
> Peter, this comes up so often, I wonder is it worth while "hiding" that 
> optional dependency behind a #define, as in:
>
> #define BOOST_SP_QA <some-header.hpp>
>
> #ifdef BOOST_SP_USE_QUICK_ALLOCATOR
> #include BOOST_SP_QA
> #endif
>

If doing that works to fool bcp, we need a better system.  It would be
a lot of work, but maybe it would be the first real use of Wave as a
library rather than just as a preprocessor.  We could use the graph
library to do a real search with some knowledge of compiler and
configuration #defines.  It would be a conservative search, so it
would follow *all* PP #ifdef branches unless it could prove that they
shouldn't be followed.  Wow, that sounds like an interesting but
difficult dynamic programming problem.  I wonder if it's even
tractable?

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com