CODEWITHSUNDEEP
pythonfiletypespython-3.x
Ray
Ray

Reputation: 8563

Python 3.3.2 check that object is of type file

I'm porting from Python 2.7 to Python 3.3.2. In Python 2.7, I used to be able to do something like assert(type(something) == file), but it seems that in Python 3.3.2 this is wrong. How do I do a similar thing in Python 3.3.2?

Upvotes: 15

Views: 17355

Answers (1)

Martijn Pieters
Martijn Pieters

Reputation: 1121416

Python 3 file objects are part of the io module, test against ABC classes in that module:

from io import IOBase

if isinstance(someobj, IOBase):

Don't use type(obj) == file in Python 2; you'd use isinstance(obj, file) instead. Even then, you would want to test for the capabilities; something the io ABCs let you do; the isinstance() function will return True for any object that implements all the methods the Abstract Base Class defines.

Demo:

>>> from io import IOBase
>>> fh = open('/tmp/demo', 'w')
>>> isinstance(fh, IOBase)
True
>>> isinstance(object(), IOBase)
False

Upvotes: 28

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