Just want to throw in my "foreach key/value" loop implementation, as an extension of "foreach", which I did years ago just as a proof of concept.
http://codereview.stackexchange.com/questions/11681/ It allows you to do: foreachkv(auto key, auto value, map) { // do sth with key / value } Its implementation follows straight out of how Q_FOREACH is implemented, just adding another for-loop. I only implemented the GCC version back then, though. On 20.02.2015 18:53, Matthew Woehlke wrote: > On 2015-02-20 07:10, Иван Комиссаров wrote: >> Sorry for interupting the discussion, but i saw mentioning of a >> range-based-for, so i have a question. std::map/unordered_map uses >> std::pair as a value type, and map::iterator::operator* returns >> reference >> to a pair, while Qt doesn't have an underlying struct and operator* >> returns >> ref to T (without a Key). So, using range-based-for (and foreach) with >> Qt >> containers doesn't allow to have an access to a key. >> Should this behavior be changed in the future (yes, this breaks source >> compatibility)? > > No. No need. (Also... note that foreach doesn't give you keys either.) > > You can instead wrap the container in an iterator wrapper that gives > you > iterators rather than values. (I have code somewhere, but not sure I > have permission to share it.) No SIC, and you can still iterate > directly > over values. > > It's not entirely unlike the trick to do: > > for (auto const i : qtIndexRange(5)) > > ...and looks like: > > for (auto const i : qtEnumerate(map)) > > Maybe it would be nice for Qt to provide one or both of these? _______________________________________________ Development mailing list Development@qt-project.org http://lists.qt-project.org/mailman/listinfo/development
