How do I correctly clean up a Python object?

Question

class Package:
    def __init__(self):
        self.files = []

    # ...

    def __del__(self):
        for file in self.files:
            os.unlink(file)
         


        

Answer 1

As an appendix to Clint's answer, you can simplify PackageResource using contextlib.contextmanager:

@contextlib.contextmanager
def packageResource():
    class Package:
        ...
    package = Package()
    yield package
    package.cleanup()

Alternatively, though probably not as Pythonic, you can override Package.__new__:

class Package(object):
    def __new__(cls, *args, **kwargs):
        @contextlib.contextmanager
        def packageResource():
            # adapt arguments if superclass takes some!
            package = super(Package, cls).__new__(cls)
            package.__init__(*args, **kwargs)
            yield package
            package.cleanup()

    def __init__(self, *args, **kwargs):
        ...

and simply use with Package(...) as package.

To get things shorter, name your cleanup function close and use contextlib.closing, in which case you can either use the unmodified Package class via with contextlib.closing(Package(...)) or override its __new__ to the simpler

class Package(object):
    def __new__(cls, *args, **kwargs):
        package = super(Package, cls).__new__(cls)
        package.__init__(*args, **kwargs)
        return contextlib.closing(package)

And this constructor is inherited, so you can simply inherit, e.g.

class SubPackage(Package):
    def close(self):
        pass