py/objstr: Return unsupported binop instead of raising TypeError.

So that user types can implement reverse operators and have them work with
str on the left-hand-side, eg `"a" + UserType()`.

Signed-off-by: Damien George <damien@micropython.org>

1 files changed, 31 insertions, 1 deletions

diff --git a/tests/basics/class_reverse_op.py b/tests/basics/class_reverse_op.py
index b0dae5f8a..11aba6aad 100644
--- a/tests/basics/class_reverse_op.py
+++ b/tests/basics/class_reverse_op.py
@@ -1,5 +1,7 @@
-class A:
+# Test reverse operators.
 
+# Test user type with integers.
+class A:
     def __init__(self, v):
         self.v = v
 
@@ -14,5 +16,33 @@ class A:
     def __repr__(self):
         return "A({})".format(self.v)
 
+
 print(A(3) + 1)
 print(2 + A(5))
+
+
+# Test user type with strings.
+class B:
+    def __init__(self, v):
+        self.v = v
+
+    def __repr__(self):
+        return "B({})".format(self.v)
+
+    def __ror__(self, o):
+        return B(o + "|" + self.v)
+
+    def __radd__(self, o):
+        return B(o + "+" + self.v)
+
+    def __rmul__(self, o):
+        return B(o + "*" + self.v)
+
+    def __rtruediv__(self, o):
+        return B(o + "/" + self.v)
+
+
+print("a" | B("b"))
+print("a" + B("b"))
+print("a" * B("b"))
+print("a" / B("b"))