[Python] Render enums as Python IntEnum (#8145)

This allows enums to be type check with mypy.
They will still behave like ints ->
> IntEnum is the same as Enum,
> but its members are also integers and can be used anywhere
> that an integer can be used.
> If any integer operation is performed with an IntEnum member,
> the resulting value loses its enumeration status.
https://docs.python.org/3/library/enum.html#enum.IntEnum

Only if the --python-typing flag is set.

src/idl_gen_python.cpp

@@ -591,12 +591,21 @@ class PythonStubGenerator {
   void GenerateEnumStub(std::stringstream &stub, const EnumDef *enum_def,
                         Imports *imports) const {
     stub << "class " << namer_.Type(*enum_def);
-    if (version_.major != 3) stub << "(object)";
+
+    if (version_.major == 3){
+      imports->Import("enum", "IntEnum");
+      stub << "(IntEnum)";
+    }
+    else {
+      stub << "(object)";
+    }
+
     stub << ":\n";
     for (const EnumVal *val : enum_def->Vals()) {
       stub << "  " << namer_.Variant(*val) << ": "
            << ScalarType(enum_def->underlying_type.base_type) << "\n";
     }
+
     if (parser_.opts.generate_object_based_api & enum_def->is_union) {
       imports->Import("flatbuffers", "table");
       stub << "def " << namer_.Function(*enum_def)
@@ -2432,7 +2441,7 @@ class PythonGenerator : public BaseGenerator {
     auto field_type = namer_.ObjectType(*ev.union_type.struct_def);
 
     code +=
-        GenIndents(1) + "if unionType == " + union_type + "()." + variant + ":";
+        GenIndents(1) + "if unionType == " + union_type + "." + variant + ":";
     if (parser_.opts.include_dependence_headers) {
       auto package_reference = GenPackageReference(ev.union_type);
       code += GenIndents(2) + "import " + package_reference;

tests/MyGame/Example/Any.py

@@ -12,13 +12,13 @@ def AnyCreator(unionType, table):
     from flatbuffers.table import Table
     if not isinstance(table, Table):
         return None
-    if unionType == Any().Monster:
+    if unionType == Any.Monster:
         import MyGame.Example.Monster
         return MyGame.Example.Monster.MonsterT.InitFromBuf(table.Bytes, table.Pos)
-    if unionType == Any().TestSimpleTableWithEnum:
+    if unionType == Any.TestSimpleTableWithEnum:
         import MyGame.Example.TestSimpleTableWithEnum
         return MyGame.Example.TestSimpleTableWithEnum.TestSimpleTableWithEnumT.InitFromBuf(table.Bytes, table.Pos)
-    if unionType == Any().MyGame_Example2_Monster:
+    if unionType == Any.MyGame_Example2_Monster:
         import MyGame.Example2.Monster
         return MyGame.Example2.Monster.MonsterT.InitFromBuf(table.Bytes, table.Pos)
     return None

tests/MyGame/Example/AnyAmbiguousAliases.py

@@ -12,13 +12,13 @@ def AnyAmbiguousAliasesCreator(unionType, table):
     from flatbuffers.table import Table
     if not isinstance(table, Table):
         return None
-    if unionType == AnyAmbiguousAliases().M1:
+    if unionType == AnyAmbiguousAliases.M1:
         import MyGame.Example.Monster
         return MyGame.Example.Monster.MonsterT.InitFromBuf(table.Bytes, table.Pos)
-    if unionType == AnyAmbiguousAliases().M2:
+    if unionType == AnyAmbiguousAliases.M2:
         import MyGame.Example.Monster
         return MyGame.Example.Monster.MonsterT.InitFromBuf(table.Bytes, table.Pos)
-    if unionType == AnyAmbiguousAliases().M3:
+    if unionType == AnyAmbiguousAliases.M3:
         import MyGame.Example.Monster
         return MyGame.Example.Monster.MonsterT.InitFromBuf(table.Bytes, table.Pos)
     return None

tests/MyGame/Example/AnyUniqueAliases.py

@@ -12,13 +12,13 @@ def AnyUniqueAliasesCreator(unionType, table):
     from flatbuffers.table import Table
     if not isinstance(table, Table):
         return None
-    if unionType == AnyUniqueAliases().M:
+    if unionType == AnyUniqueAliases.M:
         import MyGame.Example.Monster
         return MyGame.Example.Monster.MonsterT.InitFromBuf(table.Bytes, table.Pos)
-    if unionType == AnyUniqueAliases().TS:
+    if unionType == AnyUniqueAliases.TS:
         import MyGame.Example.TestSimpleTableWithEnum
         return MyGame.Example.TestSimpleTableWithEnum.TestSimpleTableWithEnumT.InitFromBuf(table.Bytes, table.Pos)
-    if unionType == AnyUniqueAliases().M2:
+    if unionType == AnyUniqueAliases.M2:
         import MyGame.Example2.Monster
         return MyGame.Example2.Monster.MonsterT.InitFromBuf(table.Bytes, table.Pos)
     return None

tests/MyGame/Example/NestedUnion/Any.py

@@ -11,10 +11,10 @@ def AnyCreator(unionType, table):
     from flatbuffers.table import Table
     if not isinstance(table, Table):
         return None
-    if unionType == Any().Vec3:
+    if unionType == Any.Vec3:
         import MyGame.Example.NestedUnion.Vec3
         return MyGame.Example.NestedUnion.Vec3.Vec3T.InitFromBuf(table.Bytes, table.Pos)
-    if unionType == Any().TestSimpleTableWithEnum:
+    if unionType == Any.TestSimpleTableWithEnum:
         import MyGame.Example.NestedUnion.TestSimpleTableWithEnum
         return MyGame.Example.NestedUnion.TestSimpleTableWithEnum.TestSimpleTableWithEnumT.InitFromBuf(table.Bytes, table.Pos)
     return None

tests/monster_test_generated.py

@@ -39,11 +39,11 @@ def AnyCreator(unionType, table):
     from flatbuffers.table import Table
     if not isinstance(table, Table):
         return None
-    if unionType == Any().Monster:
+    if unionType == Any.Monster:
         return MonsterT.InitFromBuf(table.Bytes, table.Pos)
-    if unionType == Any().TestSimpleTableWithEnum:
+    if unionType == Any.TestSimpleTableWithEnum:
         return TestSimpleTableWithEnumT.InitFromBuf(table.Bytes, table.Pos)
-    if unionType == Any().MyGame_Example2_Monster:
+    if unionType == Any.MyGame_Example2_Monster:
         return MonsterT.InitFromBuf(table.Bytes, table.Pos)
     return None
 
@@ -58,11 +58,11 @@ def AnyUniqueAliasesCreator(unionType, table):
     from flatbuffers.table import Table
     if not isinstance(table, Table):
         return None
-    if unionType == AnyUniqueAliases().M:
+    if unionType == AnyUniqueAliases.M:
         return MonsterT.InitFromBuf(table.Bytes, table.Pos)
-    if unionType == AnyUniqueAliases().TS:
+    if unionType == AnyUniqueAliases.TS:
         return TestSimpleTableWithEnumT.InitFromBuf(table.Bytes, table.Pos)
-    if unionType == AnyUniqueAliases().M2:
+    if unionType == AnyUniqueAliases.M2:
         return MonsterT.InitFromBuf(table.Bytes, table.Pos)
     return None
 
@@ -77,11 +77,11 @@ def AnyAmbiguousAliasesCreator(unionType, table):
     from flatbuffers.table import Table
     if not isinstance(table, Table):
         return None
-    if unionType == AnyAmbiguousAliases().M1:
+    if unionType == AnyAmbiguousAliases.M1:
         return MonsterT.InitFromBuf(table.Bytes, table.Pos)
-    if unionType == AnyAmbiguousAliases().M2:
+    if unionType == AnyAmbiguousAliases.M2:
         return MonsterT.InitFromBuf(table.Bytes, table.Pos)
-    if unionType == AnyAmbiguousAliases().M3:
+    if unionType == AnyAmbiguousAliases.M3:
         return MonsterT.InitFromBuf(table.Bytes, table.Pos)
     return None