Re: [Boost-users] [karma] Losing attribute?

Sebastian,

I've got a Karma generator that should emit a vector of records, writing out the index of every entry at the start. My code looks like this (note that GEOPOINT is a fusion-adapted struct of two doubles):

typedef std::vector<GEOPOINT> Contour; typedef std::vector<Contour> Poly; rule point; rule contour; rule polygon; rule start;

point = L';' << double_ << L';' << double_;

contour = L";SUBPOLYGON " << lit(_r1 - 1) << L" POINTS " << lit(phoenix::size(_val)) << L" MASK XOR" << *point;

polygon = L"POLYGON COUNT " << lit(phoenix::size(_val)) << *(contour(_a)[++_a]);

start = polygon;

This doesn't work. If I take away the modification of _a, it works, except that of course the index is 0 in every iteration. But the moment I modify _a in any way (including assigning to it anywhere in the polygon rule), suddenly contour seems to get an incorrect attribute: it never fails, but never emits points either, i.e. I get an endless string of ";SUBPOLYGON 1 POINTS 0 MASK XOR;SUBPOLYGON 2 POINTS 0 MASK XOR;SUBPOLYGON 3 POINTS 0 MASK XOR...".

Any idea why that is?

Could you please provide a minimal, but still self-contained example I could run? That would help me to give you a proper answer to your question. From what I can see your code should work just fine. Regards Hartmut --------------- Meet me at BoostCon www.boostcon.com