Paul Mensonides wrote:
-----Original Message----- From: boost-bounces@lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of Markus Schöpflin
Is there a way to get this:
scope().attr("foo") = 1; scope().attr("bar") = 2;
or this:
scope().attr("foo") = foo; scope().attr("bar") = bar;
IOW, how can I prevent macro expansion for X when invoked from PY_DEFINE_CONSTANTS()?
The only way to prevent expansion is with # and ##--and that's all about timing.
[snip solution]
The trick here is to get the sequence inside the machinery in a way that allows the machinery to prevent it from expanding. That's the trailing 'INTERCEPT_ and the 'seq ## 0'. From there, it can be immediately processed with custom sequential iteration to make a new sequence with a argument/string pairs.
I see and I'm amazed, as usual when dealing with the preprocessor. :-)
This is about the best way that you can do it, but I won't guarantee that it will work on buggy preprocessors. In fact, I know it won't work on VC. The timing is tricky, and it's intrusive on the interface, but that's about the only way that it can be done.
Fortunately I don't have to use MSVC, but you are right, the interface doesn't really look nice. I think I'll have to make a little poll at the office on what's better: PY_DEFINE_CONSTANT(foo); PY_DEFINE_CONSTANT(bar); or PY_DEFINE_CONSTANTS((foo)(bar) BOOST_PP_INTERCEPT_) Maybe we'll just stick with the simple macro then. Thanks for your help! Markus