Missing cleanup pattern (ARCH2082)

Key python.performance.dispose-pattern · Severity warning · Category performance

A class that owns a closeable resource but offers no close or context manager to release it never frees the resource. Implement the cleanup contract.

Incorrect

class Exporter:
    def __init__(self, path):
        self.file = open(path, "w")

    def write(self, row):
        self.file.write(row)

Correct

class Exporter:
    def __init__(self, path):
        self.file = open(path, "w")

    def write(self, row):
        self.file.write(row)

    def __enter__(self):
        return self

    def __exit__(self, *exc):
        self.file.close()

Fix

Add __enter__/__exit__ or close to the resource-owning class to release owned handles.