consider-using-with / R1732#

Message emitted:

Consider using 'with' for resource-allocating operations


Emitted if a resource-allocating assignment or call may be replaced by a 'with' block. By using 'with' the release of the allocated resources is ensured even in the case of an exception.

Problematic code:

file = open("apple.txt", "r", encoding="utf8")  # [consider-using-with]
contents =

worst = open("banana.txt", "r", encoding="utf8").read()  # [consider-using-with]

Correct code:

with open("apple.txt", "r", encoding="utf8") as file:
    contents =

with open("banana.txt", "r", encoding="utf8") as f:
    best =

Additional details:

Calling write() without using the with keyword or calling close() might result in the arguments of write() not being completely written to the disk, even if the program exits successfully.

This message applies to callables of Python's stdlib which can be replaced by a with statement. It is suppressed in the following cases:

  • the call is located inside a context manager

  • the call result is returned from the enclosing function

  • the call result is used in a with statement itself

Related links:

Created by the refactoring checker.