How do I write a decorator that restores the current working directory to what it was before the decorated function was called? In other words, if I use the decorator on a function that does an os.chdir()
, the cwd will not be changed after the function is called.
The answer for a decorator has been given; it works at the function definition stage as requested.
With Python 2.5+, you also have an option to do that at the function call stage using a context manager:
from __future__ import with_statement # needed for 2.5 ≤ Python < 2.6
import contextlib, os
@contextlib.contextmanager
def remember_cwd():
curdir= os.getcwd()
try: yield
finally: os.chdir(curdir)
which can be used if needed at the function call time as:
print "getcwd before:", os.getcwd()
with remember_cwd():
walk_around_the_filesystem()
print "getcwd after:", os.getcwd()
It's a nice option to have.
EDIT: I added error handling as suggested by codeape. Since my answer has been voted up, it's fair to offer a complete answer, all other issues aside.