Weakrefs to classes that derive from str

[Steven Bethard]

Ron Garret wrote:
> Why doesn't this work?
> 
>>>>from weakref import ref
>>>>class C(str): pass
> ... 
>>>>ref(C())
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
> TypeError: cannot create weak reference to 'C' object

Note that you don't need the class redirection:

py> ref('')
Traceback (most recent call last):
   File "<interactive input>", line 1, in ?
TypeError: cannot create weak reference to 'str' object

But I don't know why strings aren't valid arguments to ref...

STeVe