dir changes attributes of praw.objects.Subreddits in place

Today I noticed that the built-in function dir() seems to change the attributes of praw.objects.Subreddits in place.

Could this possibly be the result of a buggy __dir__() implementation in a praw.objects.Subreddit parent class? I honestly have no clue what to make of this.

[voussoir]

Okay, must be the difference between Python 2 and 3, that’s an interesting distinction. Does two.__dict__ instead of dir(two) cause the same thing to happen?

If this is something that can be fixed in a clean and version-compatible way, I’d say there’s no reason not to, but I’m not sure how you could change the behavior of something as basic as dir. It appears (in 3.5), that it can be overridden:

>>> class A:
...     def __dir__(self):
...             return [1, 2, 3]
...
>>>
>>> a=A()
>>> dir(a)
[1, 2, 3]

I don’t know what you would put inside that method that achieves all the normal functionality of dir and doesn’t do whatever causes Python 2 to trip the lazy loader. Plus it just seems like something that should never have to be done. You mentioned

if someone is writing a function that checks for the existence of a class method, they would get different answers for ‘description’ in dir(prog)

but I think hasattr is always the correct answer anyway. We should have a very good reason before overriding this kind of thing.

[bboe]

class Test(object):
    def __init__(self):
        self.attribute = True

    def __getattr__(self, attr):
        print('Fetching {}'.format(attr))
        return super(Test, self).__getattr__(attr)


test = Test()
print(dir(test) == dir(test))

python2 ./tmp.py 
Fetching __members__
Fetching __methods__
Fetching __members__
Fetching __methods__
True

python3 ./tmp.py 
True