Cached Decorator does not support class methods

[ktaragorn]

Cached decorator doesnt appear to support class methods. This should either be fixed somehow, or if not possible, then needs to be a loud warning in the documentation.

I just spent 1/2 - 1 hr down this rabbit hole, hope no body else has to.

This fails in a very odd way.
If a class method is used to @plugin.cached(), during the run it will appear like caching isnt working. If you restart the run, you will get the error Exception: Corrupted storage file at ...../.functions .

The file exists, and if you try to load it using storage = TimedStorage(filename, file_format, TTL) as in the file xbmcmixin.py you will get the error

(Pdb) TimedStorage(filename, file_format, TTL)
*** ValueError: File not in a supported format

Upon reading the __init__ method, I went with

(Pdb) file = open(filename,rb")
(Pdb) file.seek(0)
(Pdb) import pickle
(Pdb) pickle.load(file)
*** AttributeError: 'module' object has no attribute '<NameOfTheClassOfTheCachedMethod>'

In this case the class was just for organization so I moved this particular method out of the class and it worked just fine after that.

I understand that class instance methods may be impossible to cache between calls, but I feel (given the error, not sure) that even class level methods may not work. Either way this should be made very clear in the documentation