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. I'm not sure how big a deal this is. In TR1 the placeholders are extern, so it's not an issue. But I don't think that extern would be a good idea for boost bind. I figure if at one time it mattered to users like Yitzhak, it may matter to others again and why not give them a choice? But again, I don't fully understand why inline functions were under consideration in the first place. There use as a workaround for gcc's PCH seems to have come up years later.
Other comments:
BOOST_WORKAROUND(BOOST_GCC, <= 0x0400) is always true when the compiler isn't GCC since BOOST_GCC is not defined.
Oops! Good catch. Thanks!
Depending on the BOOST_GCC macro means that bind.hpp will not work as intended with an empty config.hpp. It did once, and I've been careful to retain this feature... not that it's being tested, or that anyone I know takes advantage of it. :-)
How about just using
#if defined(__BORLANDC__) || defined(__GNUC__) && (__GNUC__ * 100 + __GNUC_MINOR__ <= 400)
?
I just like the idea of being able to search for BOOST_WORKAROUND and find workaround specific code. I think it should be #if defined(__BORLANDC__) || (defined(BOOST_GCC) && BOOST_WORKAROUND(BOOST_GCC, <= 0x0400)) Daniel