[Python-ideas] PEP 380 close and contextmanagers? (original) (raw)

Nick Coghlan ncoghlan at gmail.com
Thu Oct 28 00:00:36 CEST 2010

On Thu, Oct 28, 2010 at 2:18 AM, Ron Adam <rrr at ronadam.com> wrote:

It looks like No context managers return values in the finally or exit part of a context manager.  Is there way to do that?

The return value from exit is used to decide whether or not to suppress the exception (i.e. bool(exit()) == True will suppress the exception that was passed in).

There are a few CMs in the test suite (test.support) that provide info about things that happened during their with statement - they all use the trick of returning a stateful object from enter, then modifying the attributes of that object in exit. I seem to recall the CM variants of unittest.TestCase.assertRaises* doing the same thing (so you can poke and prod at the raised exception yourself). warnings.catch_warnings also appends encountered warnings to a list returned by enter when record=True.

Cheers, Nick.

-- Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

More information about the Python-ideas mailing list