[Boost-users] POSIX regex library conflicts

From: Andrew Dennison (adenniso_at_[hidden])
Date: 2004-11-19 09:52:18

My project hit an interesting snag yesterday.  It turns out that in 
different areas of the project, one developer had been using the boost 
regex library, while the other was using the POSIX library.  Since the 
boost regex library provides POSIX compatibility with boost/regex.h i 
suspect you may already be aware of this, but i'll mention it anyway, as i 
believe more could be done about this problem.

regex.h uses #defines for certain numerical constants which are 
also declared in boost regex.  This is a problem if both posix and boost 
are defined in the same project at the same time as the preprocessor will 
replace the boost definitions with the macro definition in regex.h (ie 
REG_EXTENDED = 1, among others).

I appreciate that this case is somewhat handled by the compatibility 
header, but this isn't always an available solution.  We were able to 
change headers, so this problem was solved, but this may not always be 
possible (ie third party software).  Perhaps the developers could include 
some protection against this kind of error by checking to see if 
the offending constants are defined before the boost declarations are 
made and #undef-ing them as needed.  This kind of error can be difficult 
to track down in mid-large projects.

Regards,
Andrew.