Re: [boost] Macros at namespace scope: trailing semicolon?

From: Dave Steffen (dgsteffen_at_[hidden])
Date: 2005-10-14 18:47:26

Hey Folks,

  Coming back to this topic after several months...

Paul Mensonides writes:

 > Well, here's a BOOST_SEMICOLON definition, in case anyone is interested (no
 > #include-guard required):
 > 
 > // <boost/semicolon.hpp>
 > 
 > namespace boost { namespace empty { } }
 > 
 > #define BOOST_SEMICOLON \
 >     using namespace ::boost::empty \
 >     /**/
 > 
 > It doesn't introduce any names into the scope where it is used, and
 > it can be used any number of times in the same scope.  It can be
 > used at namespace and function scope, though it is not necessary at
 > function scope.  It *can't* be used in class scope, but it isn't
 > necessary there either.

 It turns out that, in some places where we've got heavy macro
 programming going on, this didn't work; I kept getting "expected
 nested-name-specifier before 'namespace' " sorts of errors.  It turns
 out that

#define BOOST_SEMICOLON
  typedef int semicolon_allowed_after_this

 makes GCC 3.4 happier; I don't understand the grammar issues
 involved.

 ... just a report from the trenches. :-)

------------------------------------------------------------------------
Dave Steffen, Ph.D.      On a paper submitted by a physicist colleague:
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