Re: [Matplotlib-users] Grouper use

[Eric F. <ef...@ha...>]

TP wrote:
> Hi everybody,
> 
> I try to play with "sharex" feature. Then, I have been guided to the
> class "Grouper" of module cbook:
> 
> http://matplotlib.sourceforge.net/api/cbook_api.html
> 
> So I tried the following example:
> 
> ##############################
> from matplotlib.cbook import *
> 
> g = Grouper()
> g.join('a', 'b')
> ##############################
> 
> I obtain:
> 
> Traceback (most recent call last):
>   File "test_grouper.py", line 4, in <module>
>     g.join('a', 'b')
>   File ".../matplotlib/cbook.py", line 1118, in join
>     set_a = mapping.setdefault(ref(a), [ref(a)])
> TypeError: cannot create weak reference to 'str' object
> 
> What is the problem?

Grouper is implemented using weak references, which are supported only 
for some types of objects, as described here:
http://docs.python.org/library/weakref.html

Evidently the cbook Grouper docstring was written when the 
implementation was different, and did not use weakref.  So, you have 
found a major bug in the docstring.

Eric

> 
> Thanks in advance,
> 
> Julien
>