| Home | Libraries | People | FAQ | More

### Pairs

Since the containers use `std::pair` they're limited to the version from the current standard library. But since C++11 `std::pair`'s `piecewise_construct` based constructor is very useful, `emplace` emulates it with a `piecewise_construct` in the `boost::unordered` namespace. So for example, the following will work:

    boost::unordered_multimap<std::string, std::complex> x;

    x.emplace(
        boost::unordered::piecewise_construct,
        boost::make_tuple("key"), boost::make_tuple(1, 2));

Older drafts of the standard also supported variadic constructors for `std::pair`, where the first argument would be used for the first part of the pair, and the remaining for the second part.