Issue1929

__len__ of new-style classes should raise OverflowError instead of TypeError for compatibility with CPython.

$ jython2.7
Jython 2.7.0a2+ (default:2cc31de620ba+, cze 17 2012, 09:04:11) 
[OpenJDK 64-Bit Server VM (Oracle Corporation)] on java1.7.0_03-icedtea
Type "help", "copyright", "credits" or "license" for more information.
>>> class X(object):
...     def __len__(self):
...         return 2 ** 70
... 
>>> len(X())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: __len__ should return a int
>>>
$ python2.7
Python 2.7.3+ (2.7:0add70dd3c43+, Jun 17 2012, 04:30:39) 
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> class X(object):
...     def __len__(self):
...         return 2 ** 70
... 
>>> len(X())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: long int too large to convert to int
>>>
$ python3.2
Python 3.2.3+ (3.2:714b8f91f3d4+, Jun 17 2012, 04:59:08) 
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> class X:
...     def __len__(self):
...         return 2 ** 70
... 
>>> len(X())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
OverflowError: cannot fit 'int' into an index-sized integer
>>>

The attached patch seems to introduce behavior identical to CPython's behavior.

This patch breaks when a type returns a long that can fit into an int (e.g. 3L) or a faux-int (a type that implements __int__).

What you want is to return res.asInt() and it should take care of all those details. A test would be nice too (unless there's already some in the stdlib, which I hope there are =] )

Arfrever: have you had a chance to submit a contributor agreement yet?

Attached patch changes object.derived template to use asInt in order for __len__ methods to convert longs that fit in an int value to be returned or throw OverflowError otherwise.

Target beta 4

I have verified that __len__asInt.patch will throw an overflow error on new style classes. I've applied the template to PyObjectDerived and written a test case for that. 

I've signed the contributor license agreement and my bugs.python.org user id is lpan78.

Fixed as of https://hg.python.org/jython/rev/41d5032ef380, applying Indra's patch as the fix, and a new test case. Thanks Luoxi for suggesting a test, but I needed something that was more comprehensive.