Hi Daniel,
For sets (o.a. interval_set), the following operators are appropriate, as also used in Boost.dynamic_bitset: &= for intersection |= for union ^= for symmetric difference -= for difference So this is how it is implemented but I would remove += as a synonym for |=
For interval_map, it is currently much less clear to me now. The operators do two things at the same time, which is confusing me. ...
I won't be able to review ITL, but I would like to comment that I think that this issue of operators needs to be resolved before ITL is included in Boost.
Since I wrote that above, I'll react on this. I didn't intend such a reaction in my review. The ITL library is excellent, the thing (and the only thing I found) which was not logical (in my opinion, maybe Joachim will explain it all) is that the -= operator is not the set theoretic difference but the mathematical subtraction of values. I really don't think that this is a major concern. Regards, Barend