Function bind_map

include/pybind11/stl_bind.h:734–856

template <typename Map, typename holder_type = default_holder_type<Map>, typename... Args>
class_<Map, holder_type> bind_map(handle scope, const std::string &name, Args &&...args) {
    using KeyType = typename Map::key_type;
    using MappedType = typename Map::mapped_type;
    using KeysView = detail::keys_view;
    using ValuesView = detail::values_view;
    using ItemsView = detail::items_view;
    using Class_ = class_<Map, holder_type>;

    // If either type is a non-module-local bound type then make the map binding non-local as well;
    // otherwise (e.g. both types are either module-local or converting) the map will be
    // module-local.
    auto *tinfo = detail::get_type_info(typeid(MappedType));
    bool local = !tinfo || tinfo->module_local;
    if (local) {
        tinfo = detail::get_type_info(typeid(KeyType));
        local = !tinfo || tinfo->module_local;
    }

    Class_ cl(scope, name.c_str(), pybind11::module_local(local), std::forward<Args>(args)...);

    // Wrap KeysView if it wasn't already wrapped
    if (!detail::get_type_info(typeid(KeysView))) {
        class_<KeysView> keys_view(scope, "KeysView", pybind11::module_local(local));
        keys_view.def("__len__", &KeysView::len);
        keys_view.def("__iter__",
                      &KeysView::iter,
                      keep_alive<0, 1>() /* Essential: keep view alive while iterator exists */
        );
        keys_view.def("__contains__", &KeysView::contains);
    }
    // Similarly for ValuesView:
    if (!detail::get_type_info(typeid(ValuesView))) {
        class_<ValuesView> values_view(scope, "ValuesView", pybind11::module_local(local));
        values_view.def("__len__", &ValuesView::len);
        values_view.def("__iter__",
                        &ValuesView::iter,
                        keep_alive<0, 1>() /* Essential: keep view alive while iterator exists */
        );
    }
    // Similarly for ItemsView:
    if (!detail::get_type_info(typeid(ItemsView))) {
        class_<ItemsView> items_view(scope, "ItemsView", pybind11::module_local(local));
        items_view.def("__len__", &ItemsView::len);
        items_view.def("__iter__",
                       &ItemsView::iter,
                       keep_alive<0, 1>() /* Essential: keep view alive while iterator exists */
        );
    }

    cl.def(init<>());

    // Register stream insertion operator (if possible)
    detail::map_if_insertion_operator<Map, Class_>(cl, name);

    cl.def(
        "__bool__",
        [](const Map &m) -> bool { return !m.empty(); },
        "Check whether the map is nonempty");