implemented dynamic equality and inequality for PyObject instances

lostmsu · filmor · commit e84731f8e883 · 2022-07-05T21:35:59.000+02:00
fixed unhandled Python errors during comparison attempts fixes #1848
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -45,6 +45,8 @@ details about the cause of the failure
      able to access members that are part of the implementation class, but not the
      interface.  Use the new `__implementation__` or `__raw_implementation__` properties to
      if you need to "downcast" to the implementation class.
+-   BREAKING: `==` and `!=` operators on `PyObject` instances now use Python comparison
+     (previously was equivalent to `object.ReferenceEquals(,)`)
 -   BREAKING: Parameters marked with `ParameterAttributes.Out` are no longer returned in addition
      to the regular method return value (unless they are passed with `ref` or `out` keyword).
 -   BREAKING: Drop support for the long-deprecated CLR.* prefix.
diff --git a/src/embed_tests/dynamic.cs b/src/embed_tests/dynamic.cs
@@ -128,6 +128,28 @@ public void PassPyObjectInNet()
             Assert.IsTrue(sys.testattr1.Equals(sys.testattr2));
         }
 
+        // regression test for https://github.com/pythonnet/pythonnet/issues/1848
+        [Test]
+        public void EnumEquality()
+        {
+            using var scope = Py.CreateScope();
+            scope.Exec(@"
+import enum
+
+class MyEnum(enum.IntEnum):
+    OK = 1
+    ERROR = 2
+
+def get_status():
+    return MyEnum.OK 
+"
+);
+
+            dynamic MyEnum = scope.Get("MyEnum");
+            dynamic status = scope.Get("get_status").Invoke();
+            Assert.IsTrue(status == MyEnum.OK);
+        }
+
         // regression test for https://github.com/pythonnet/pythonnet/issues/1680
         [Test]
         public void ForEach()
diff --git a/src/runtime/PythonTypes/PyObject.cs b/src/runtime/PythonTypes/PyObject.cs
@@ -1075,12 +1075,9 @@ public virtual bool Equals(PyObject? other)
             {
                 return true;
             }
-            int r = Runtime.PyObject_Compare(this, other);
-            if (Exceptions.ErrorOccurred())
-            {
-                throw PythonException.ThrowLastAsClrException();
-            }
-            return r == 0;
+            int result = Runtime.PyObject_RichCompareBool(obj, other.obj, Runtime.Py_EQ);
+            if (result < 0) throw PythonException.ThrowLastAsClrException();
+            return result != 0;
         }
 
 
@@ -1304,6 +1301,18 @@ public override bool TryConvert(ConvertBinder binder, out object? result)
             return false;
         }
 
+        private bool TryCompare(PyObject arg, int op, out object @out)
+        {
+            int result = Runtime.PyObject_RichCompareBool(this.obj, arg.obj, op);
+            @out = result != 0;
+            if (result < 0)
+            {
+                Exceptions.Clear();
+                return false;
+            }
+            return true;
+        }
+        
         public override bool TryBinaryOperation(BinaryOperationBinder binder, object arg, out object? result)
         {
             using var _ = Py.GIL();
@@ -1352,32 +1361,29 @@ public override bool TryBinaryOperation(BinaryOperationBinder binder, object arg
                     res = Runtime.PyNumber_InPlaceXor(this.obj, ((PyObject)arg).obj);
                     break;
                 case ExpressionType.GreaterThan:
-                    result = Runtime.PyObject_Compare(this.obj, ((PyObject)arg).obj) > 0;
-                    return true;
+                    return this.TryCompare((PyObject)arg, Runtime.Py_GT, out result);
                 case ExpressionType.GreaterThanOrEqual:
-                    result = Runtime.PyObject_Compare(this.obj, ((PyObject)arg).obj) >= 0;
-                    return true;
+                    return this.TryCompare((PyObject)arg, Runtime.Py_GE, out result);
                 case ExpressionType.LeftShift:
                     res = Runtime.PyNumber_Lshift(this.obj, ((PyObject)arg).obj);
                     break;
                 case ExpressionType.LeftShiftAssign:
                     res = Runtime.PyNumber_InPlaceLshift(this.obj, ((PyObject)arg).obj);
                     break;
                 case ExpressionType.LessThan:
-                    result = Runtime.PyObject_Compare(this.obj, ((PyObject)arg).obj) < 0;
-                    return true;
+                    return this.TryCompare((PyObject)arg, Runtime.Py_LT, out result);
                 case ExpressionType.LessThanOrEqual:
-                    result = Runtime.PyObject_Compare(this.obj, ((PyObject)arg).obj) <= 0;
-                    return true;
+                    return this.TryCompare((PyObject)arg, Runtime.Py_LE, out result);
                 case ExpressionType.Modulo:
                     res = Runtime.PyNumber_Remainder(this.obj, ((PyObject)arg).obj);
                     break;
                 case ExpressionType.ModuloAssign:
                     res = Runtime.PyNumber_InPlaceRemainder(this.obj, ((PyObject)arg).obj);
                     break;
                 case ExpressionType.NotEqual:
-                    result = Runtime.PyObject_Compare(this.obj, ((PyObject)arg).obj) != 0;
-                    return true;
+                    return this.TryCompare((PyObject)arg, Runtime.Py_NE, out result);
+                case ExpressionType.Equal:
+                    return this.TryCompare((PyObject)arg, Runtime.Py_EQ, out result);
                 case ExpressionType.Or:
                     res = Runtime.PyNumber_Or(this.obj, ((PyObject)arg).obj);
                     break;
@@ -1402,6 +1408,40 @@ public override bool TryBinaryOperation(BinaryOperationBinder binder, object arg
             return true;
         }
 
+        public static bool operator ==(PyObject? a, PyObject? b)
+        {
+            if (a is null && b is null)
+            {
+                return true;
+            }
+            if (a is null || b is null)
+            {
+                return false;
+            }
+
+            using var _ = Py.GIL();
+            int result = Runtime.PyObject_RichCompareBool(a.obj, b.obj, Runtime.Py_EQ);
+            if (result < 0) throw PythonException.ThrowLastAsClrException();
+            return result != 0;
+        }
+
+        public static bool operator !=(PyObject? a, PyObject? b)
+        {
+            if (a is null && b is null)
+            {
+                return false;
+            }
+            if (a is null || b is null)
+            {
+                return true;
+            }
+
+            using var _ = Py.GIL();
+            int result = Runtime.PyObject_RichCompareBool(a.obj, b.obj, Runtime.Py_NE);
+            if (result < 0) throw PythonException.ThrowLastAsClrException();
+            return result != 0;
+        }
+
         // Workaround for https://bugzilla.xamarin.com/show_bug.cgi?id=41509
         // See https://github.com/pythonnet/pythonnet/pull/219
         internal static object? CheckNone(PyObject pyObj)
@@ -1436,14 +1476,17 @@ public override bool TryUnaryOperation(UnaryOperationBinder binder, out object?
                 case ExpressionType.Not:
                     r = Runtime.PyObject_Not(this.obj);
                     result = r == 1;
+                    if (r == -1) Exceptions.Clear();
                     return r != -1;
                 case ExpressionType.IsFalse:
                     r = Runtime.PyObject_IsTrue(this.obj);
                     result = r == 0;
+                    if (r == -1) Exceptions.Clear();
                     return r != -1;
                 case ExpressionType.IsTrue:
                     r = Runtime.PyObject_IsTrue(this.obj);
                     result = r == 1;
+                    if (r == -1) Exceptions.Clear();
                     return r != -1;
                 case ExpressionType.Decrement:
                 case ExpressionType.Increment:
diff --git a/src/runtime/Runtime.cs b/src/runtime/Runtime.cs
@@ -962,31 +962,6 @@ internal static IntPtr PyObject_CallObject(IntPtr pointer, IntPtr args)
 
         internal static int PyObject_RichCompareBool(BorrowedReference value1, BorrowedReference value2, int opid) => Delegates.PyObject_RichCompareBool(value1, value2, opid);
 
-        internal static int PyObject_Compare(BorrowedReference value1, BorrowedReference value2)
-        {
-            int res;
-            res = PyObject_RichCompareBool(value1, value2, Py_LT);
-            if (-1 == res)
-                return -1;
-            else if (1 == res)
-                return -1;
-
-            res = PyObject_RichCompareBool(value1, value2, Py_EQ);
-            if (-1 == res)
-                return -1;
-            else if (1 == res)
-                return 0;
-
-            res = PyObject_RichCompareBool(value1, value2, Py_GT);
-            if (-1 == res)
-                return -1;
-            else if (1 == res)
-                return 1;
-
-            Exceptions.SetError(Exceptions.SystemError, "Error comparing objects");
-            return -1;
-        }
-
 
         internal static int PyObject_IsInstance(BorrowedReference ob, BorrowedReference type) => Delegates.PyObject_IsInstance(ob, type);
 
