In-Reply-To: <4276462D.1020501@boost-consulting.com> eric@boost-consulting.com (Eric Niebler) wrote (abridged):
It injects 5 local variables. I haven't checked, but I suspect that some can be optimized away sometimes.
I doubt they will be in debug mode, which is when I need to look at them.
I'm not sure why users will need to understand how FOREACH uses its hidden variables. Can you explain?
When I am debugging, I need to understand what the code is doing else how I can I understand what it is doing wrong? For example, from looking at the implementation it seems that the macro caches the end() value in a variable called _foreach_end. This means that if some random memory corruption changes that variable the loop may never terminate. I need to know. Incidently, if it is caching then code like: BOOST_FOREACH( int i, vec ) if (condition(i)) vec.push_back( filter(i) ); will not work the same as: for (iterator i = vec.begin(); i != vec.end(); ++i) if (condition(*i)) vec.push_back( filter(*i) ); Which at least needs to be documented. Again the implementation is complex enough that I can't tell at a glance whether these are the same, so I may have this wrong, but I strongly suspect they are different. -- Dave Harris, Nottingham, UK.