bugfix: removing typing and duplicate `class_` for KeysView/ValuesView/ItemsView. Fix #4529 (#4985)

* remove typing for KeysView/ValuesView/ItemsView

* add tests for map view types

include/pybind11/stl_bind.h

@@ -645,49 +645,50 @@ auto map_if_insertion_operator(Class_ &cl, std::string const &name)
         "Return the canonical string representation of this map.");
 }
 
-template <typename KeyType>
 struct keys_view {
     virtual size_t len() = 0;
     virtual iterator iter() = 0;
-    virtual bool contains(const KeyType &k) = 0;
+    virtual bool contains(const handle &k) = 0;
-    virtual bool contains(const object &k) = 0;
     virtual ~keys_view() = default;
 };
 
-template <typename MappedType>
 struct values_view {
     virtual size_t len() = 0;
     virtual iterator iter() = 0;
     virtual ~values_view() = default;
 };
 
-template <typename KeyType, typename MappedType>
 struct items_view {
     virtual size_t len() = 0;
     virtual iterator iter() = 0;
     virtual ~items_view() = default;
 };
 
-template <typename Map, typename KeysView>
+template <typename Map>
-struct KeysViewImpl : public KeysView {
+struct KeysViewImpl : public detail::keys_view {
     explicit KeysViewImpl(Map &map) : map(map) {}
     size_t len() override { return map.size(); }
     iterator iter() override { return make_key_iterator(map.begin(), map.end()); }
-    bool contains(const typename Map::key_type &k) override { return map.find(k) != map.end(); }
+    bool contains(const handle &k) override {
-    bool contains(const object &) override { return false; }
+        try {
+            return map.find(k.template cast<typename Map::key_type>()) != map.end();
+        } catch (const cast_error &) {
+            return false;
+        }
+    }
     Map &map;
 };
 
-template <typename Map, typename ValuesView>
+template <typename Map>
-struct ValuesViewImpl : public ValuesView {
+struct ValuesViewImpl : public detail::values_view {
     explicit ValuesViewImpl(Map &map) : map(map) {}
     size_t len() override { return map.size(); }
     iterator iter() override { return make_value_iterator(map.begin(), map.end()); }
     Map &map;
 };
 
-template <typename Map, typename ItemsView>
+template <typename Map>
-struct ItemsViewImpl : public ItemsView {
+struct ItemsViewImpl : public detail::items_view {
     explicit ItemsViewImpl(Map &map) : map(map) {}
     size_t len() override { return map.size(); }
     iterator iter() override { return make_iterator(map.begin(), map.end()); }
@@ -700,11 +701,9 @@ template <typename Map, typename holder_type = std::unique_ptr<Map>, typename...
 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 StrippedKeyType = detail::remove_cvref_t<KeyType>;
+    using KeysView = detail::keys_view;
-    using StrippedMappedType = detail::remove_cvref_t<MappedType>;
+    using ValuesView = detail::values_view;
-    using KeysView = detail::keys_view<StrippedKeyType>;
+    using ItemsView = detail::items_view;
-    using ValuesView = detail::values_view<StrippedMappedType>;
-    using ItemsView = detail::items_view<StrippedKeyType, StrippedMappedType>;
     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;
@@ -718,39 +717,20 @@ class_<Map, holder_type> bind_map(handle scope, const std::string &name, Args &&
     }
 
     Class_ cl(scope, name.c_str(), pybind11::module_local(local), std::forward<Args>(args)...);
-    static constexpr auto key_type_descr = detail::make_caster<KeyType>::name;
-    static constexpr auto mapped_type_descr = detail::make_caster<MappedType>::name;
-    std::string key_type_name(key_type_descr.text), mapped_type_name(mapped_type_descr.text);
 
-    // If key type isn't properly wrapped, fall back to C++ names
+    // Wrap KeysView if it wasn't already wrapped
-    if (key_type_name == "%") {
-        key_type_name = detail::type_info_description(typeid(KeyType));
-    }
-    // Similarly for value type:
-    if (mapped_type_name == "%") {
-        mapped_type_name = detail::type_info_description(typeid(MappedType));
-    }
-
-    // Wrap KeysView[KeyType] if it wasn't already wrapped
     if (!detail::get_type_info(typeid(KeysView))) {
-        class_<KeysView> keys_view(
+        class_<KeysView> keys_view(scope, "KeysView", pybind11::module_local(local));
-            scope, ("KeysView[" + key_type_name + "]").c_str(), 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__",
+        keys_view.def("__contains__", &KeysView::contains);
-                      static_cast<bool (KeysView::*)(const KeyType &)>(&KeysView::contains));
-        // Fallback for when the object is not of the key type
-        keys_view.def("__contains__",
-                      static_cast<bool (KeysView::*)(const object &)>(&KeysView::contains));
     }
     // Similarly for ValuesView:
     if (!detail::get_type_info(typeid(ValuesView))) {
-        class_<ValuesView> values_view(scope,
+        class_<ValuesView> values_view(scope, "ValuesView", pybind11::module_local(local));
-                                       ("ValuesView[" + mapped_type_name + "]").c_str(),
-                                       pybind11::module_local(local));
         values_view.def("__len__", &ValuesView::len);
         values_view.def("__iter__",
                         &ValuesView::iter,
@@ -759,10 +739,7 @@ class_<Map, holder_type> bind_map(handle scope, const std::string &name, Args &&
     }
     // Similarly for ItemsView:
     if (!detail::get_type_info(typeid(ItemsView))) {
-        class_<ItemsView> items_view(
+        class_<ItemsView> items_view(scope, "ItemsView", pybind11::module_local(local));
-            scope,
-            ("ItemsView[" + key_type_name + ", ").append(mapped_type_name + "]").c_str(),
-            pybind11::module_local(local));
         items_view.def("__len__", &ItemsView::len);
         items_view.def("__iter__",
                        &ItemsView::iter,
@@ -788,25 +765,19 @@ class_<Map, holder_type> bind_map(handle scope, const std::string &name, Args &&
 
     cl.def(
         "keys",
-        [](Map &m) {
+        [](Map &m) { return std::unique_ptr<KeysView>(new detail::KeysViewImpl<Map>(m)); },
-            return std::unique_ptr<KeysView>(new detail::KeysViewImpl<Map, KeysView>(m));
-        },
         keep_alive<0, 1>() /* Essential: keep map alive while view exists */
     );
 
     cl.def(
         "values",
-        [](Map &m) {
+        [](Map &m) { return std::unique_ptr<ValuesView>(new detail::ValuesViewImpl<Map>(m)); },
-            return std::unique_ptr<ValuesView>(new detail::ValuesViewImpl<Map, ValuesView>(m));
-        },
         keep_alive<0, 1>() /* Essential: keep map alive while view exists */
     );
 
     cl.def(
         "items",
-        [](Map &m) {
+        [](Map &m) { return std::unique_ptr<ItemsView>(new detail::ItemsViewImpl<Map>(m)); },
-            return std::unique_ptr<ItemsView>(new detail::ItemsViewImpl<Map, ItemsView>(m));
-        },
         keep_alive<0, 1>() /* Essential: keep map alive while view exists */
     );
 

tests/test_stl_binders.cpp

@@ -192,6 +192,16 @@ TEST_SUBMODULE(stl_binders, m) {
     py::bind_map<std::unordered_map<std::string, double const>>(m,
                                                                 "UnorderedMapStringDoubleConst");
 
+    // test_map_view_types
+    py::bind_map<std::map<std::string, float>>(m, "MapStringFloat");
+    py::bind_map<std::unordered_map<std::string, float>>(m, "UnorderedMapStringFloat");
+
+    py::bind_map<std::map<std::pair<double, int>, int32_t>>(m, "MapPairDoubleIntInt32");
+    py::bind_map<std::map<std::pair<double, int>, int64_t>>(m, "MapPairDoubleIntInt64");
+
+    py::bind_map<std::map<int, py::object>>(m, "MapIntObject");
+    py::bind_map<std::map<std::string, py::object>>(m, "MapStringObject");
+
     py::class_<E_nc>(m, "ENC").def(py::init<int>()).def_readwrite("value", &E_nc::value);
 
     // test_noncopyable_containers

tests/test_stl_binders.py

@@ -317,9 +317,9 @@ def test_map_view_types():
     map_string_double_const = m.MapStringDoubleConst()
     unordered_map_string_double_const = m.UnorderedMapStringDoubleConst()
 
-    assert map_string_double.keys().__class__.__name__ == "KeysView[str]"
+    assert map_string_double.keys().__class__.__name__ == "KeysView"
-    assert map_string_double.values().__class__.__name__ == "ValuesView[float]"
+    assert map_string_double.values().__class__.__name__ == "ValuesView"
-    assert map_string_double.items().__class__.__name__ == "ItemsView[str, float]"
+    assert map_string_double.items().__class__.__name__ == "ItemsView"
 
     keys_type = type(map_string_double.keys())
     assert type(unordered_map_string_double.keys()) is keys_type
@@ -336,6 +336,30 @@ def test_map_view_types():
     assert type(map_string_double_const.items()) is items_type
     assert type(unordered_map_string_double_const.items()) is items_type
 
+    map_string_float = m.MapStringFloat()
+    unordered_map_string_float = m.UnorderedMapStringFloat()
+
+    assert type(map_string_float.keys()) is keys_type
+    assert type(unordered_map_string_float.keys()) is keys_type
+    assert type(map_string_float.values()) is values_type
+    assert type(unordered_map_string_float.values()) is values_type
+    assert type(map_string_float.items()) is items_type
+    assert type(unordered_map_string_float.items()) is items_type
+
+    map_pair_double_int_int32 = m.MapPairDoubleIntInt32()
+    map_pair_double_int_int64 = m.MapPairDoubleIntInt64()
+
+    assert type(map_pair_double_int_int32.values()) is values_type
+    assert type(map_pair_double_int_int64.values()) is values_type
+
+    map_int_object = m.MapIntObject()
+    map_string_object = m.MapStringObject()
+
+    assert type(map_int_object.keys()) is keys_type
+    assert type(map_string_object.keys()) is keys_type
+    assert type(map_int_object.items()) is items_type
+    assert type(map_string_object.items()) is items_type
+
 
 def test_recursive_vector():
     recursive_vector = m.RecursiveVector()