NotImplemented return value misinterpreted in new classes

[dubnerm]

BPO	847024
Nosy	@mwhudson, @birkenfeld, @birkenfeld

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = 'https://github.com/mwhudson'
closed_at = <Date 2006-02-20.19:53:50.000>
created_at = <Date 2003-11-22.02:39:43.000>
labels = ['interpreter-core']
title = 'NotImplemented return value misinterpreted in new classes'
updated_at = <Date 2006-02-20.19:53:50.000>
user = 'https://bugs.python.org/dubnerm'

bugs.python.org fields:

activity = <Date 2006-02-20.19:53:50.000>
actor = 'georg.brandl'
assignee = 'mwh'
closed = True
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2003-11-22.02:39:43.000>
creator = 'dubnerm'
dependencies = []
files = []
hgrepos = []
issue_num = 847024
keywords = []
message_count = 3.0
messages = ['19086', '19087', '19088']
nosy_count = 4.0
nosy_names = ['mwh', 'georg.brandl', 'georg.brandl', 'dubnerm']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue847024'
versions = ['Python 2.3']

[dubnerm]

Following program:
------------------------------ notimpl.py
class CClassic:
def __add__(self, other):
return NotImplemented
def __mul__(self, other):
return NotImplemented
class CNew(object):
def __add__(self, other):
return NotImplemented
def __mul__(self, other):
return NotImplemented

a=CClassic()
try:
  print a+2
except Exception, e:
  print e
try:
  print a*2
except Exception, e:
  print e
a=CNew()
try:
  print a+2
except Exception, e:
  print e
try:
  print a*2
except Exception, e:
  print e

---

Output following (correct) under Python 2.2:

unsupported operand types for +: 'instance' and 'int'
unsupported operand type(s) for *: 'instance' and 'int'
unsupported operand types for +: 'CNew' and 'int'
unsupported operand type(s) for *: 'CNew' and 'int'

And following (wrong) under Python 2.3[.2]:

unsupported operand type(s) for +: 'instance' and 'int'
unsupported operand type(s) for *: 'instance' and 'int'
unsupported operand type(s) for +: 'CNew' and 'int'
NotImplemented

[birkenfeld]

Logged In: YES
user_id=1188172

I could reproduce with all my Pythons. I looked around a bit
but couldn't find any cause of this. Michael, do you have
more luck?

[birkenfeld]

Logged In: YES
user_id=849994

This now seems to be fixed in 2.5 HEAD and 2.4 branch. Cheers!