Question

I am new to Python and feel confused about when I should call close.

For instance, consider this example from the csv documentation.

import csv
with open('some.csv', 'rb') as f:
    reader = csv.reader(f)
    for row in reader:
        print row

There is no reader.close() in the end of this task.

Q> How do I find out whether or not a function call need to be followed by a close call?

Answer 1

Functions that return resources that need to be cleaned up will have documentation that explains that. csv.reader doesn’t open a file, or otherwise create a closable resource. The open call does, but the with statement takes care of closing it for you.