2013/2/21 Jan Hudec <bulb@ucw.cz>
Hello All,
Doing some heavy template work on collections of pairs and tuples I came across the need for functors returning tuple and pair members. So I looked whether Boost has anything like that, but couldn't find any.
Now the functors can be written using bind like:
bind(_1, &TupleType::get<3>); bind(_1, &PairType::first);
except that requires explicitly mentioning the tuple/pair type. Trying to use simply
&boost::tuples::get<3, WHAT?!?!?>
even failed for me as boost::tuples::get is actually a 3-argument template based on boost::tuples::cons, which looks like implementation detail I better not rely on. Besides bost methods involve pointer-to-{function,member}, which might interfere with inlining.
So I think it would be convenient to have functions like this somewhere in boost:
Phoenix actually has `at` for Fusion, you can use it. (Somewhat I can't find the doc) May be used like: phx::at_c<n>(phx::_1) Also be sure to include the related Fusion file for adapting boost::tuple.