AttrDict is not a dict

[rbu]

The project description ready:

A dictionary that allows attribute-style access.

However, I discovered:

> from attrdict import AttrDict
> a = AttrDict()
> isinstance(a, dict)
False

Is there a reason AttrDict is not extending dict? It also makes it impossible to use AttrDict as a "drop in" replacement in existing APIs.
Consider an API that used to return (or receive) a dict and could be switched to an AttrDict.

[bcj]

AttrDict subclasses collections.MutableMapping which is what dict, collections.OrderedDict, collections.defaultdict, and collections.Counter all extend (incidentally none of those others subclass dict either). As far as I know, this is the recommended solution (perhaps a holdover from the time when it was impossible to subclass dict).

In most cases someone doing an insinstance(_, dict), people should probably be using insinstance(_, collections.Mapping) or insinstance(_, collections.MutableMapping). In the worst case scenario, you can always just cast it to a dict.

I've thus far avoided subclassing dict because I'm not convinced the remaining unimplemented methods are worth reducing the key-space. Which means I should probably reword it as "Can be used most places a dict can".

If you are in a situation in which you need AttrDict to subclass dict (or it would otherwise make things much easier), I'd very much appreciate it if you could comment on this issue (#21). The change would be somewhat bigger and I'm trying to gauge interest.

I'm going to close this issue as it's resolution/non-resolution will be the same as the linked issue.