Fix __slots__ bug (#44)

[liwt31]

fix the bug by another try/except and add a test for it.

[laike9m]

Thanks for the fix, I neglected the missing __dict__ issue. There are a few problems in this commit, see comments below.

[liwt31]

I'm sorry but I can't see any comments. GitHub has some issue yesterday, maybe your comment is rolled back?

[laike9m]

Cause I didn't submit them yesterday.

[liwt31]

I've tried to implement a version based on the idea of making __slots__ a property of attributes, Here's an example:

>>> class A:
...     __slots__ = ['__mul__', '__hash__', 'a', 'b']
>>> pdir(A())
special attribute:
    __class__, __doc__, __module__, __slots__
abstract class:
    __subclasshook__
arithmetic:
    __mul__(slotted)
object customization:
    __format__, __hash__(slotted), __init__, __new__, __repr__, __sizeof__, __str__
rich comparison:
    __eq__, __ge__, __gt__, __le__, __lt__, __ne__
attribute access:
    __delattr__, __dir__, __getattribute__, __setattr__
class customization:
    __init_subclass__
pickle:
    __reduce__, __reduce_ex__
descriptor:
    a(slotted): class member_descriptor with getter, setter, deleter
    b(slotted): class member_descriptor with getter, setter, deleter

[laike9m]

LGTM. Thanks for the great work and quick responses!

[liwt31]

And thanks for your comments and advice! It's a pleasure having discussions with you.