allow subtypes in right operand to override left side parent class behaviour...

allow subtypes in right operand to override left side parent class behaviour for "@" operator (Python tries "__rmatmul__()" first in this case), generally clean up code duplication while at it

Cython/Utility/ObjectHandling.c

@@ -1398,31 +1398,30 @@ bad:
     return result;
 }
 
+#define __Pyx_TryMatrixMethod(x, y, py_method_name) {                   \
+    PyObject *func = __Pyx_PyObject_GetAttrStr(x, py_method_name);      \
+    if (func) {                                                         \
+        PyObject *result = __Pyx_PyObject_CallMatrixMethod(func, y);    \
+        if (result != Py_NotImplemented)                                \
+            return result;                                              \
+        Py_DECREF(result);                                              \
+    } else {                                                            \
+        if (!PyErr_ExceptionMatches(PyExc_AttributeError))              \
+            return NULL;                                                \
+        PyErr_Clear();                                                  \
+    }                                                                   \
+}
+
 static PyObject* __Pyx__PyNumber_MatrixMultiply(PyObject* x, PyObject* y, const char* op_name) {
-    PyObject *func;
-    // FIXME: make subtype aware
-    // see note at https://docs.python.org/3/reference/datamodel.html#emulating-numeric-types
-    func = __Pyx_PyObject_GetAttrStr(x, PYIDENT("__matmul__"));
-    if (func) {
-        PyObject *result = __Pyx_PyObject_CallMatrixMethod(func, y);
-        if (result != Py_NotImplemented)
-            return result;
-        Py_DECREF(result);
-    } else {
-        if (!PyErr_ExceptionMatches(PyExc_AttributeError))
-            return NULL;
-        PyErr_Clear();
+    int right_is_subtype = PyObject_IsSubclass((PyObject*)Py_TYPE(y), (PyObject*)Py_TYPE(x));
+    if (right_is_subtype) {
+        // to allow subtypes to override parent behaviour, try reversed operation first
+        // see note at https://docs.python.org/3/reference/datamodel.html#emulating-numeric-types
+        __Pyx_TryMatrixMethod(y, x, PYIDENT("__rmatmul__"))
     }
-    func = __Pyx_PyObject_GetAttrStr(y, PYIDENT("__rmatmul__"));
-    if (func) {
-        PyObject *result = __Pyx_PyObject_CallMatrixMethod(func, x);
-        if (result != Py_NotImplemented)
-            return result;
-        Py_DECREF(result);
-    } else {
-        if (!PyErr_ExceptionMatches(PyExc_AttributeError))
-            return NULL;
-        PyErr_Clear();
+    __Pyx_TryMatrixMethod(x, y, PYIDENT("__matmul__"))
+    if (!right_is_subtype) {
+        __Pyx_TryMatrixMethod(y, x, PYIDENT("__rmatmul__"))
     }
     PyErr_Format(PyExc_TypeError,
                  "unsupported operand type(s) for %.2s: '%.100s' and '%.100s'",
@@ -1433,18 +1432,9 @@ static PyObject* __Pyx__PyNumber_MatrixMultiply(PyObject* x, PyObject* y, const
 }
 
 static PyObject* __Pyx_PyNumber_InPlaceMatrixMultiply(PyObject* x, PyObject* y) {
-    PyObject *func;
-    func = __Pyx_PyObject_GetAttrStr(x, PYIDENT("__imatmul__"));
-    if (func) {
-        PyObject *result = __Pyx_PyObject_CallMatrixMethod(func, y);
-        if (result != Py_NotImplemented)
-            return result;
-        Py_DECREF(result);
-    } else {
-        if (!PyErr_ExceptionMatches(PyExc_AttributeError))
-            return NULL;
-        PyErr_Clear();
-    }
+    __Pyx_TryMatrixMethod(x, y, PYIDENT("__imatmul__"))
     return __Pyx__PyNumber_MatrixMultiply(x, y, "@=");
 }
+
+#undef __Pyx_TryMatrixMethod
 #endif