inspect.getargspec() is deprecated and will be removed in Python 3.6

When using PRAW with the recently released Python 3.5 a warning shows:

DeprecationWarning: inspect.getargspec() is deprecated, use inspect.signature() instead

Python's documentation on inspect.getargspec() says:

Deprecated since version 3.0: Use signature() and Signature Object, which provide a better introspecting API for callables. This function will be removed in Python 3.6.

In the file praw/decorators.py the function inspect.getargspec() is used twice, to get a list of a function arguments' names, both lines are identical:

func_args = inspect.getargspec(function).args

This can easily be made compatible with Python 3.6 by changing the two lines to:

func_args = list(inspect.signature(function).parameters.keys())

which, to my knowledge, produces the exact same list of arguments' names so it should work with the rest of the code.

But, the problem is that the inspect.signature() function, added in Python 3.0, wasn't backported to Python 2.7 and thus isn't supported by Python 2.

That's the limit of my skills I'm afraid. I'm not a programmer experienced enough to know what to do in such a case, I don't know how PRAW can be made compatible with both python 2.7 and 3.6, so instead of a pull request I can only open a new issue.

[13steinj]

But, the problem is that the inspect.signature() function, added in Python 3.0, wasn't backported to Python 2.7 and thus isn't supported by Python 2.

Using the six compatability library, the use of Python 2/3 can be determined via the boolean six.PY(x) where x is 2 or 3, and the function used can be different per that check. Or the function from 2.7 can just be imported as the one with the 3 name with a try except block. But both function should be double checked to produce an equivalent result.

[jaccarmac]

inspect.getargspec(function).args and list(inspect.signature(function).parameters.keys()) are not, in fact, equivalent. The former returns a list of positional arguments while the latter returns the names of all arguments. The list comprehension [parameter.name for parameter in inspect.signature(function).parameters.values() if parameter.kind == parameter.POSITIONAL_OR_KEYWORD] gives you what you want for functions with *args or **kwargs.

[bboe]

@macioosch thanks for reporting, and @jaccarmac thanks for the information. Would either of you like to make a PR for fixing this such that the function also works 3.5+?

[13steinj]

@bboe I'll do it right now since I have the time.

@jaccarmac I believe your mistaken? I just tested it:

>>> def foo(thing1, thing2, thing3, thing4=None, thing5=None):
...     print('\n'.join([str(thing1), str(thing2), str(thing3), str(thing4), str(thing5)]))
...     return str(thing5)
... 
>>> foo('bar', 'biz', 'bang')
bar
biz
bang
None
None
'None'
>>> inspect.getargspec(foo).args['thing1', 'thing2', 'thing3', 'thing4', 'thing5']
>>> list(inspect.signature(foo).parameters.keys())['thing1', 'thing2', 'thing3', 'thing4', 'thing5']
>>> 

They both return all arguments, unless I'm misunderstanding what a positional argument is.

Edit: I see what @jaccarmac was talking about now, whoops. If there's a *args or **kwargs those get returned in the signarure.