Issue 5176: special-case string formatting in BINARY_MODULO implementation. This shows a modest (1-3%) speed-up in templating systems, for example.
diff --git a/Lib/test/test_opcodes.py b/Lib/test/test_opcodes.py
index d7d1673..7985bf6 100644
--- a/Lib/test/test_opcodes.py
+++ b/Lib/test/test_opcodes.py
@@ -102,6 +102,12 @@
g = eval('lambda a=1: None')
self.assertNotEquals(f, g)
+ def test_modulo_of_string_subclasses(self):
+ class MyString(str):
+ def __mod__(self, value):
+ return 42
+ self.assertEqual(MyString() % 3, 42)
+
def test_main():
run_unittest(OpcodeTest)
diff --git a/Python/ceval.c b/Python/ceval.c
index d457fd5..419ecfa 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -1283,7 +1283,10 @@
case BINARY_MODULO:
w = POP();
v = TOP();
- x = PyNumber_Remainder(v, w);
+ if (PyString_CheckExact(v))
+ x = PyString_Format(v, w);
+ else
+ x = PyNumber_Remainder(v, w);
Py_DECREF(v);
Py_DECREF(w);
SET_TOP(x);