<br><br><div class="gmail_quote">On 19 November 2011 23:11, Vinay Sajip <span dir="ltr"><<a href="mailto:vinay_sajip@yahoo.co.uk">vinay_sajip@yahoo.co.uk</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div class="im">Michael Foord <fuzzyman <at> <a href="http://voidspace.org.uk" target="_blank">voidspace.org.uk</a>> writes:<br>
<br>
> That works fine in Python 3 (mock.Mock does it):<br>
><br>
> >>> class Foo(object):<br>
> ... @property<br>
> ... def __class__(self):<br>
> ... return int<br>
> ...<br>
> >>> a = Foo()<br>
> >>> isinstance(a, int)<br>
> True<br>
> >>> a.__class__<br>
> <class 'int'><br>
><br>
> There must be something else going on here.<br>
><br>
<br>
</div>Michael, thanks for the quick response. Okay, I'll dig in a bit further: the<br>
definition in SimpleLazyObject is<br>
<br>
__class__ = property(new_method_proxy(operator.attrgetter("__class__")))<br>
<br>
so perhaps the problem is something related to the specifics of the definition.<br>
Here's what I found in initial exploration:<br>
<br>
--------------------------------------------------------------------------<br>
Python 2.7.2+ (default, Oct 4 2011, 20:06:09)<br>
[GCC 4.6.1] on linux2<br>
Type "help", "copyright", "credits" or "license" for more information.<br>
>>> from django.utils.functional import SimpleLazyObject<br>
>>> fake_bool = SimpleLazyObject(lambda: True)<br>
>>> fake_bool.__class__<br>
<type 'bool'><br>
>>> fake_bool.__dict__<br>
{'_setupfunc': <function <lambda> at 0xca9ed8>, '_wrapped': True}<br>
>>> SimpleLazyObject.__dict__<br>
dict_proxy({<br>
'__module__': 'django.utils.functional',<br>
'__nonzero__': <function inner at 0xca9de8>,<br>
'__deepcopy__': <function __deepcopy__ at 0xca9c08>,<br>
'__str__': <function inner at 0xca9b18>,<br>
'_setup': <function _setup at 0xca9aa0>,<br>
'__class__': <property object at 0xca5730>,<br>
'__hash__': <function inner at 0xca9d70>,<br>
'__unicode__': <function inner at 0xca9b90>,<br>
'__bool__': <function inner at 0xca9de8>,<br>
'__eq__': <function inner at 0xca9cf8>,<br>
'__doc__': '\n A lazy object initialised from any function.\n\n<br>
Designed for compound objects of unknown type. For builtins or<br>
objects of\n known type, use django.utils.functional.lazy.\n ',<br>
'__init__': <function __init__ at 0xca9a28><br>
})<br>
--------------------------------------------------------------------------<br>
Python 3.2.2 (default, Sep 5 2011, 21:17:14)<br>
[GCC 4.6.1] on linux2<br>
Type "help", "copyright", "credits" or "license" for more information.<br>
>>> from django.utils.functional import SimpleLazyObject<br>
>>> fake_bool = SimpleLazyObject(lambda : True)<br>
>>> fake_bool.__class__<br>
<class 'django.utils.functional.SimpleLazyObject'><br>
>>> fake_bool.__dict__<br>
{<br>
'_setupfunc': <function <lambda> at 0x1c36ea8>,<br>
'_wrapped': <object object at 0x1d88b70><br>
}<br>
>>> SimpleLazyObject.__dict__<br>
dict_proxy({<br>
'__module__': 'django.utils.functional',<br>
'__nonzero__': <function inner at 0x1f56490>,<br>
'__deepcopy__': <function __deepcopy__ at 0x1f562f8>,<br>
'__str__': <function inner at 0x1f561e8>,<br>
'_setup': <function _setup at 0x1f56160>,<br>
'__hash__': <function inner at 0x1f56408>,<br>
'__unicode__': <function inner at 0x1f56270>,<br>
'__bool__': <function inner at 0x1f56490>,<br>
'__eq__': <function inner at 0x1f56380>,<br>
'__doc__': '\n A lazy object initialised from any function.\n\n<br>
Designed for compound objects of unknown type. For builtins or<br>
objects of\n known type, use django.utils.functional.lazy.\n ',<br>
'__init__': <function __init__ at 0x1f560d8><br>
})<br>
--------------------------------------------------------------------------<br>
<br>
In Python 3, there's no __class__ property as there is in Python 2,<br>
the fake_bool's type isn't bool, and the callable to set up the wrapped<br>
object never gets called (which is why _wrapped is not set to True, but to<br>
an anonymous object - this is set in SimpleLazyObject.__init__).<br>
<br></blockquote><div><br>The Python compiler can do strange things with assignment to __class__ in the presence of super. This issue has now been fixed, but it may be what is biting you:<br><br> <a href="http://bugs.python.org/issue12370">http://bugs.python.org/issue12370</a><br>
<br>If this *is* the problem, then see the workaround suggested in the issue. (alias super to _super in the module scope and use the old style super calling convention.)<br><br>Michael<br><br> </div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Puzzling!<br>
<br>
Regards,<br>
<font color="#888888"><br>
Vinay Sajip<br>
</font><div><div></div><div class="h5"><br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br><pre cols="72"><a href="http://www.voidspace.org.uk/" target="_blank">http://www.voidspace.org.uk/</a><br><br>May you do good and not evil<br>May you find forgiveness for yourself and forgive others<br>
May you share freely, never taking more than you give.<br>-- the sqlite blessing <a href="http://www.sqlite.org/different.html" target="_blank">http://www.sqlite.org/different.html</a></pre>
<br>