Daniel Walker wrote:
On 5/9/07, Peter Dimov <pdimov@mmltd.net> wrote:
Daniel Walker wrote:
I've attached a patch that leaves borland and g++ <= 4.0 as they were. I also changed my little addition to the documentation to reflect this. And one more thing, I couldn't find a macro analogous to BOOST_MSVC for gcc's version number that I could use with BOOST_WORKAROUND. I added one (BOOST_GCC) in boost/config/compilers/gcc.hpp that does the same things as MPL's gcc config file. Let me know if there's some other way this should have been done.
I'd like to understand the motivation behind BOOST_BIND_ENABLE_INLINE_PLACEHOLDERS.
I'm not sure if I entirely understand it either. ;-)
I was trying to figure out why the placeholders were implemented as functions at all. Apparently, around version 1.5 of placeholders.h, inline functions were introduced for all compilers based on a suggestion from Yitzhak Sapir. I haven't gone back through the list archives to see what was under discussion at that time, but I assumed that an inline function implementation saved some overhead in the .data sections of object files. Or perhaps there was some other reasons that made defining the objects repeatedly in each compilation unit unattractive.
See http://lists.boost.org/Archives/boost/2002/03/26490.php and the associated thread. The specific 1.5 change is caused by Borland PCH problems. 1.6 has probably come right after one regression test cycle. placeholders.hpp has evolved into its current form since many compilers prefer one of the implementations and have problems with the others, especially when using precompiled headers.