Merge pull request #313 from jagerman/scoped-enums

Fix scoped enums and add scoped enum example

example/example-constants-and-functions.cpp

@@ -14,6 +14,11 @@ enum EMyEnumeration {
     ESecondEntry
 };
 
+enum class ECMyEnum {
+    Two = 2,
+    Three
+};
+
 class ExampleWithEnum {
 public:
     enum EMode {
@@ -41,6 +46,10 @@ float test_function3(int i) {
     return (float) i / 2.f;
 }
 
+void test_ecenum(ECMyEnum z) {
+    std::cout << "test_ecenum(ECMyEnum::" << (z == ECMyEnum::Two ? "Two" : "Three") << ")" << std::endl;
+}
+
 py::bytes return_bytes() {
     const char *data = "\x01\x00\x02\x00";
     return std::string(data, 4);
@@ -56,6 +65,7 @@ void init_ex_constants_and_functions(py::module &m) {
     m.def("test_function", &test_function1);
     m.def("test_function", &test_function2);
     m.def("test_function", &test_function3);
+    m.def("test_ecenum", &test_ecenum);
     m.attr("some_constant") = py::int_(14);
 
     py::enum_<EMyEnumeration>(m, "EMyEnumeration")
@@ -63,6 +73,11 @@ void init_ex_constants_and_functions(py::module &m) {
         .value("ESecondEntry", ESecondEntry)
         .export_values();
 
+    py::enum_<ECMyEnum>(m, "ECMyEnum")
+        .value("Two", ECMyEnum::Two)
+        .value("Three", ECMyEnum::Three)
+        ;
+
     py::class_<ExampleWithEnum> exenum_class(m, "ExampleWithEnum");
     exenum_class.def_static("test_function", &ExampleWithEnum::test_function);
     py::enum_<ExampleWithEnum::EMode>(exenum_class, "EMode")

example/example-constants-and-functions.py

@@ -6,6 +6,7 @@ sys.path.append('.')
 from example import test_function
 from example import some_constant
 from example import EMyEnumeration
+from example import ECMyEnum, test_ecenum
 from example import EFirstEntry
 from example import ExampleWithEnum
 from example import return_bytes
@@ -20,6 +21,27 @@ print(test_function())
 print(test_function(7))
 print(test_function(EMyEnumeration.EFirstEntry))
 print(test_function(EMyEnumeration.ESecondEntry))
+test_ecenum(ECMyEnum.Three)
+z = ECMyEnum.Two
+test_ecenum(z)
+try:
+    z == 2
+    print("Bad: expected a TypeError exception")
+except TypeError:
+    try:
+        z != 3
+        print("Bad: expected a TypeError exception")
+    except TypeError:
+        print("Good: caught expected TypeError exceptions for scoped enum ==/!= int comparisons")
+
+y = EMyEnumeration.ESecondEntry
+try:
+    y == 2
+    y != 2
+    print("Good: no TypeError exception for unscoped enum ==/!= int comparisions")
+except TypeError:
+    print("Bad: caught TypeError exception for unscoped enum ==/!= int comparisons")
+
 print("enum->integer = %i" % int(EMyEnumeration.ESecondEntry))
 print("integer->enum = %s" % str(EMyEnumeration(2)))
 

example/example-constants-and-functions.ref

@@ -10,6 +10,10 @@ test_function(enum=1)
 None
 test_function(enum=2)
 None
+test_ecenum(ECMyEnum::Three)
+test_ecenum(ECMyEnum::Two)
+Good: caught expected TypeError exceptions for scoped enum ==/!= int comparisons
+Good: no TypeError exception for unscoped enum ==/!= int comparisions
 enum->integer = 2
 integer->enum = EMyEnumeration.ESecondEntry
 A constant = 14

include/pybind11/pybind11.h

@@ -1019,9 +1019,14 @@ public:
         this->def("__init__", [](Type& value, UnderlyingType i) { new (&value) Type((Type) i); });
         this->def("__int__", [](Type value) { return (UnderlyingType) value; });
         this->def("__eq__", [](const Type &value, Type *value2) { return value2 && value == *value2; });
-        this->def("__eq__", [](const Type &value, UnderlyingType value2) { return value == value2; });
         this->def("__ne__", [](const Type &value, Type *value2) { return !value2 || value != *value2; });
-        this->def("__ne__", [](const Type &value, UnderlyingType value2) { return value != value2; });
+        if (std::is_convertible<Type, UnderlyingType>::value) {
+            // Don't provide comparison with the underlying type if the enum isn't convertible,
+            // i.e. if Type is a scoped enum, mirroring the C++ behaviour.  (NB: we explicitly
+            // convert Type to UnderlyingType below anyway because this needs to compile).
+            this->def("__eq__", [](const Type &value, UnderlyingType value2) { return (UnderlyingType) value == value2; });
+            this->def("__ne__", [](const Type &value, UnderlyingType value2) { return (UnderlyingType) value != value2; });
+        }
         this->def("__hash__", [](const Type &value) { return (UnderlyingType) value; });
         m_entries = entries;
     }