[pypy-svn] pypy default: Test and fix for an obscure case.

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: 
Changeset: r42281:99f9d995f74c
Date: 2011-02-25 14:36 +0100
http://bitbucket.org/pypy/pypy/changeset/99f9d995f74c/

Log:	Test and fix for an obscure case.

diff --git a/pypy/module/__builtin__/test/test_builtin.py b/pypy/module/__builtin__/test/test_builtin.py
--- a/pypy/module/__builtin__/test/test_builtin.py
+++ b/pypy/module/__builtin__/test/test_builtin.py
@@ -166,6 +166,12 @@
         assert sum([1,2,3]) ==6
         assert sum([],5) ==5
         assert sum([1,2,3],4) ==10
+        #
+        class Foo(object):
+            def __radd__(self, other):
+                assert other is None
+                return 42
+        assert sum([Foo()], None) == 42
 
     def test_type_selftest(self):
         assert type(type) is type

diff --git a/pypy/module/__builtin__/functional.py b/pypy/module/__builtin__/functional.py
--- a/pypy/module/__builtin__/functional.py
+++ b/pypy/module/__builtin__/functional.py
@@ -329,15 +329,13 @@
         result_w.append(w_res)
     return result_w
 
-def sum(space, w_sequence, w_start=None):
+def sum(space, w_sequence, w_start=0):
     """sum(sequence[, start]) -> value
 
 Returns the sum of a sequence of numbers (NOT strings) plus the value
 of parameter 'start' (which defaults to 0).  When the sequence is
 empty, returns start."""
-    if space.is_w(w_start, space.w_None):
-        w_start = space.wrap(0)
-    elif space.is_true(space.isinstance(w_start, space.w_basestring)):
+    if space.is_true(space.isinstance(w_start, space.w_basestring)):
         msg = "sum() can't sum strings"
         raise OperationError(space.w_TypeError, space.wrap(msg))
     w_iter = space.iter(w_sequence)