Rob Hunter Rob Hunter - 4 months ago 13
Python Question

Right way to clean up a temporary folder in Python class

I am creating a class in which I want to generate a temporary workspace of folders that will persist for the life of the object and then be removed. I am using tempfile.mkdtemp() in the def init to create the space, but I have read that I can't rely on del being called.

I am wanting something like this:

class MyClass:
def __init__(self):
self.tempfolder = tempfile.mkdtemp()

def ... #other stuff

def __del__(self):
if os.path.exists(self.tempfolder): shutil.rmtree(self.tempfolder)


Is there another/better way to handle this clean up? I was reading about 'with' but it appears to only be helpful within a function.

Answer

Caveat: you can never guarantee that the temp folder will be deleted, because the user could always hard kill your process and then it can't run anything else.

That said, do

temp_dir = tempfile.mkdtemp()
try:
    <some code>
finally:
    shutil.rmtree(temp_dir)

Since this is a very common operation, Python has a special way to encapsulate "do something, execute code, clean up": a context manager. You can write your own as follows:

@contextlib.contextmanager
def make_temp_directory():
    temp_dir = tempfile.mkdtemp()
    try:
        yield temp_dir
    finally:
        shutil.rmtree(temp_dir)

and use it as

with make_temp_directory() as temp_dir:
    <some code>

(Note that this uses the @contextlib.contextmanager shortcut to make a context manager. If you want to implement one the original way, you need to make a custom class with __enter__ and __exit__ methods; the __enter__ would create and return the temp directory and the __exit__ delete it.