CODEWITHSUNDEEP
pythonpython-3.xfilefile-iowith-statement
rahul rachh
rahul rachh

Reputation: 99

Difference between f.close(), f.close and f.closed

with open('new.txt', 'r+') as f:
    print(f.readline())


if f.close:
    print('It is closed')
else:
    print('It is open.')

If I run this code, outputs 'It is closed'. However, if I change the if statement from f.close to f.closed(), I get the output 'It is open'. So is my file closed or open? Why am I getting different outputs?

Upvotes: 0

Views: 10397

Answers (2)

CDJB
CDJB

Reputation: 14506

f.close is a reference to the close method of the file object, so always evaluates as True when read as a boolean. f.close() is a call to that method, which does not return anything, so will always evaluate to False, as bool(None) evaluates to False. f.closed is a boolean attribute which tells us whether or not the file is closed. If you alter your code to:

if f.closed:
    print('It is closed')
else:
    print('It is open.')

This will return the result you expect. As you have used with ... as f, your file will be closed automatically after you leave the scope of that statement, so you don't have to worry about using f.close() anyway.

Upvotes: 11

johannesack
johannesack

Reputation: 678

f.close is the function object, and as such using if f.close does not call the function. if f.close thus always evaluates as True. Further, if the method did not exist, it would not return False, it would provide a syntax error.

>>> type(f.close)
<class 'builtin_function_or_method'>
>>> type(f.doesnotexist)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: '_io.TextIOWrapper' object has no attribute 'doesnotexist'

You can check what if f.close will evaluate to by checking what the bool(.) function returns:

>>> bool(f.close)
True

From which we can see that this evaluates to true.

f.closed is the member that tells you whether your file has been closed (which with does automatically), f.close() closes your file.

f.closed() raises a TypeError, because f.closed is a boolean and thus can not be called:

>>> f.closed()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'bool' object is not callable

Upvotes: 1

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