[IronPython] Bug in Django's lazy functions

[Curt Hagenlocher]

By the way, you can see the same behavior from CPython if you do this:
from functional import lazy

def foo():
    return "foo"

f = lazy(foo, str)
print str.strip(f())

Builtin functions and magical proxies don't appear to work well together...

On Mon, Dec 29, 2008 at 8:43 AM, Curt Hagenlocher <curt at hagenlocher.org>wrote:

> This specific error seems to come down to the fact that IronPython
> implements str.__cmp__ while CPython apparently does not.
>
> PS C:\src> ipyd
> IronPython 2.0 Beta (2.0.0.5000) on .NET 2.0.50727.3069
> Type "help", "copyright", "credits" or "license" for more information.
> >>> str.__cmp__
> <method '__cmp__' of 'str' objects>
> >>> ^Z
>
> PS C:\src> C:\Python25\python.exe
> Python 2.5.2 (r252:60911, Feb 21 2008, 13:11:45) [MSC v.1310 32 bit
> (Intel)] on win32
> Type "help", "copyright", "credits" or "license" for more information.
> >>> str.__cmp__
> <method-wrapper '__cmp__' of type object at 0x1E1E30C0>
> >>>
>
> What happens is that IronPython ends up calling str.__cmp__, which
> correctly reports that its argument isn't a string.  CPython apparently
> calls object.__cmp__ (or something masquerading as it) which is much less
> picky.  It seems to me that this code is overly sensitive to something that
> should be an implementation detail, but we'd obviously like to provide a way
> to work around it.  Please add this to CodePlex.
>
> There may also be a problem as a result of str == unicode; in fact, there's
> a commented-out assertion in line 175 of functional.py that specifically
> breaks because this is true.
>
> On Sun, Dec 28, 2008 at 4:41 PM, Jeff Hardy <jdhardy at gmail.com> wrote:
>
>> Hi all,
>> I've been on the trail of this bug for months, and I think I've
>> finally caught a piece of it. I've uploaded a somewhat-minimal repro
>> to
>> http://cid-414fa1a9bd174b4b.skydrive.live.com/self.aspx/Public/lazy_cmp.zip.
>> functional.py<http://cid-414fa1a9bd174b4b.skydrive.live.com/self.aspx/Public/lazy_cmp.zip.functional.py>is taken from Django and is used extensively by it. The
>> lazy() function, in particular, has some hairy code in it to enable
>> lazy objects that seems to be where this problem originates.
>>
>> The output of lazy_cmp.py is differsbetween IP 2.0 and Python 2.5:
>> >python lazy_cmp.py
>> 1
>>
>> >ipy lazy_cmp.py
>> Traceback (most recent call last):
>>  File "lazy_cmp.py", line 13, in lazy_cmp.py
>>  File "C:\Users\Jeff\Desktop\lazy_cmp\functional.py", line 191, in
>> __wrapper__
>> TypeError: expected str, got Object_1$6
>>
>> Hopefully the fix is simple, as this completely breaks Django's admin
>> views.
>>
>> - Jeff
>>
>> _______________________________________________
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>>
>>
>
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