Supporting export in the future

From: Daryle Walker (darylew_at_[hidden])
Date: 2001-10-22 13:16:44

Supposedly, some compilers (Comeau?) are going to support "export" soon.
Maybe we could support it like this:

*   Use a BOOST_NO_EXPORT config macro for compilers that can't support
"export".  This is currently every compiler, but we can't use the reverse
test since "export" is supposed to be standard.

*   Consider going to a centralized mandatory-source directory, to ease
using "export" headers.  Let's call this directory $BOOST_ROOT/boost_src.
If a compiler doesn't support "export", a header could end with:

#ifndef BOOST_NO_EXPORT
#include <boost_src/crc.cpp>
#endif

otherwise, the user has to include the *.cpp file in the project makefile
like regular non-template source files.  Having a centralized directory is
better than having to pick out directories all over the "libs" hierarchy.

*   Compilers that don't support "export" may not even handle the word
showing up in a declaration or definition.  Maybe we should do something
like BOOST_NESTED_TEMPLATE to safely mark declarations:

#ifndef BOOST_NO_EXPORT
#define BOOST_DECLARE_EXPORT  export
#else
#define BOOST_DECLARE_EXPORT
#endif

*   The latest release of Spirit (1.2.1) is an example of where the *.ipp
files could transition to this new model.  The existing mandatory source
files could transition to this model too.

Thoughts?

-- 
Daryle Walker
Mac, Internet, and Video Game Junkie
darylew AT mac DOT com