I propose that __enter__ and __exit__ be added to subprocess.Popen.  __enter__ returns self, __exit__ closes open file descriptors.

__exit__ could also do the same checks that __del__ does (and which I don’t entirely understand.

See also os.popen (os._wrap_close).

Here's a patch which implements the context manager and adds a few tests and a small doc change.

Tested on Mac and Windows.

Thanks!  Patch looks good, tests pass and doc builds.

I have one question and two micro-nitpicks on http://codereview.appspot.com/3441041/

I updated the doc to be much more simple. I got used to sys.executable based tests :) New patch attached.

As for __del__, I think it should do it's thing, and the exit will do it's own. Context managers are traditionally used on file-based things, or things that can be opened or closed. Creating a Popen object will open one or more pipes, so we should just close those opened pipes.

New doc looks good. Suggested changes: make with a link, explaing why it’s a context manager.

-   Popen objects are supported as context managers via the ``with`` statement.
+   Popen objects are supported as context managers via the :keyword:`with`` statement, so that file descriptors are closed cleanly.

I agree with your view on __del__ vs. __exit__.

:keyword:`with`` → :keyword:`with`

Committed in r86951. Thanks for the reviews!

“closing any open file descriptors on exit” is exactly the perfect wording I was looking for.  Thanks for the patch!