Client can be pickled and unpickled

[jussih]

Implements #18

[SendGridDX]

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[jussih]

Checking up on this. Are there any issues that would block this from being merged? Any requests for further changes?

[logannc]

This is incomplete without also exposing __reduce__ and __reduce_ex__.

A more complete fix here would be, in addition to exposing __getstate__ and __setstate__, to add something like below to the top of the implementation of __getattr__:

try:
    return super(Client, self).__getattr__(name)
except AttributeError as e:
    pass

This will be sure to allow the user to access anything defined on the python object (including __reduce__ and __reduce_ex__, etc). You still need to add the functions you've added as they don't have default implementations on object so pickling utilities will break when they check hasattr(o, '__getstate__') and assume it is what it normally is, rather than a new object, etc.

An even MORE complete fix is to NOT return a new object when it looks like a double underscore function - I think it is a reasonable limitation to the user experience to require special care / disallowing the shortcut syntax when your API happens to look like special Python functions (much like the explanation states in the docstring of Client._(self, name).

try:
    return super(Client, self).__getattr__(name)
except AttributeError as e:
    if name.startswith('__') and name.endswith('__'):
        raise e

[jussih]

__reduce__ and __reduce_ex__ are not necessary here, since the instance contains only data types Pickle can handle with the higher level interface of __getstate__ and __setstate__. A test case provided in the PR demonstrates a successful pickling and unpickling of an instance.

You are correct about the potential problems in __getattr__ and it merits an issue of it's own, but I still maintain this PR resolves this issue. Or can you provide an example of a failed pickling?

[logannc]

Huh. I thought I had an example Friday night, but I can't remember what it was. I guess I assumed it was required because it was originally failing on line 495 in pickle.py which implied it was defaulting to __reduce_ex__. I guess it uses __getstate__ and __setstate__ first elsewhere.

I'm still not convinced I didn't have an example. I feel like I'll run into it later. If I do, I'll let you know. Otherwise, carry on! :)

[thinkingserious]

Hello @jussih,

Thanks again for the PR!

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