Michael Foord <fuzzyman <at> voidspace.org.uk> writes:
> That works fine in Python 3 (mock.Mock does it):
>
> >>> class Foo(object):
> ... @property
> ... def __class__(self):
> ... return int
> ...
> >>> a = Foo()
> >>> isinstance(a, int)
> True
> >>> a.__class__
> <class 'int'>
>
> There must be something else going on here.
>
Michael, thanks for the quick response. Okay, I'll dig in a bit further: the
definition in SimpleLazyObject is
__class__ = property(new_method_proxy(operator.attrgetter("__class__")))
so perhaps the problem is something related to the specifics of the definition.
Here's what I found in initial exploration:
--------------------------------------------------------------------------
Python 2.7.2+ (default, Oct 4 2011, 20:06:09)
[GCC 4.6.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from django.utils.functional import SimpleLazyObject
>>> fake_bool = SimpleLazyObject(lambda: True)
>>> fake_bool.__class__
<type 'bool'>
>>> fake_bool.__dict__
{'_setupfunc': <function <lambda> at 0xca9ed8>, '_wrapped': True}
>>> SimpleLazyObject.__dict__
dict_proxy({
'__module__': 'django.utils.functional',
'__nonzero__': <function inner at 0xca9de8>,
'__deepcopy__': <function __deepcopy__ at 0xca9c08>,
'__str__': <function inner at 0xca9b18>,
'_setup': <function _setup at 0xca9aa0>,
'__class__': <property object at 0xca5730>,
'__hash__': <function inner at 0xca9d70>,
'__unicode__': <function inner at 0xca9b90>,
'__bool__': <function inner at 0xca9de8>,
'__eq__': <function inner at 0xca9cf8>,
'__doc__': '\n A lazy object initialised from any function.\n\n
Designed for compound objects of unknown type. For builtins or
objects of\n known type, use django.utils.functional.lazy.\n ',
'__init__': <function __init__ at 0xca9a28>
})
--------------------------------------------------------------------------
Python 3.2.2 (default, Sep 5 2011, 21:17:14)
[GCC 4.6.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from django.utils.functional import SimpleLazyObject
>>> fake_bool = SimpleLazyObject(lambda : True)
>>> fake_bool.__class__
<class 'django.utils.functional.SimpleLazyObject'>
>>> fake_bool.__dict__
{
'_setupfunc': <function <lambda> at 0x1c36ea8>,
'_wrapped': <object object at 0x1d88b70>
}
>>> SimpleLazyObject.__dict__
dict_proxy({
'__module__': 'django.utils.functional',
'__nonzero__': <function inner at 0x1f56490>,
'__deepcopy__': <function __deepcopy__ at 0x1f562f8>,
'__str__': <function inner at 0x1f561e8>,
'_setup': <function _setup at 0x1f56160>,
'__hash__': <function inner at 0x1f56408>,
'__unicode__': <function inner at 0x1f56270>,
'__bool__': <function inner at 0x1f56490>,
'__eq__': <function inner at 0x1f56380>,
'__doc__': '\n A lazy object initialised from any function.\n\n
Designed for compound objects of unknown type. For builtins or
objects of\n known type, use django.utils.functional.lazy.\n ',
'__init__': <function __init__ at 0x1f560d8>
})
--------------------------------------------------------------------------
In Python 3, there's no __class__ property as there is in Python 2,
the fake_bool's type isn't bool, and the callable to set up the wrapped
object never gets called (which is why _wrapped is not set to True, but to
an anonymous object - this is set in SimpleLazyObject.__init__).
Puzzling!
Regards,
Vinay Sajip
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