On Tue, 19 Nov 2019 at 12:03, Paul Moore <p.f.mo...@gmail.com> wrote: > > On Tue, 19 Nov 2019 at 11:34, Oscar Benjamin <oscar.j.benja...@gmail.com> > wrote: > > > If I was to propose anything here it would not be to disallow anything > > that you can currently do with context managers. Rather the suggestion > > would be to: > > 1. Clearly define what a well-behaved context manager is. > > 2. Add convenient utilities for working with well behaved context managers. > > 3. Add well-behaved alternatives for open and maybe others. > > 4. Add Random832's utility for adapting misbehaving context managers. > > That sounds reasonable, with one proviso. I would *strongly* object to > calling context managers that conform to the new expectations "well > behaved", and by contrast implying that those that don't are somehow > "misbehaving". File objects have been considered as perfectly > acceptable context managers since the first introduction of context > managers (so have locks, and zipfile objects, which might also fall > foul of the new requirements). Suddenly deeming them as "misbehaving" > is unreasonable.
Perhaps a less emotive way of distinguishing these classes of context managers would be as "eager" vs "lazy". An eager context manager jumps the gun and does whatever needs undoing or following up before its __enter__ method is called. A lazy context manager waits until __enter__ is called before committing itself. I don't really want to give a sense of equality between eager and lazy though. To me it is clear that lazy context managers are preferable. You say it's unreasonable to claim now that some long-existing context managers are "misbehaving". Perhaps there is a better word but an alternative that implies that all existing context managers are "perfectly acceptable" will not convey the useful point that some ways of doing things are better than others. -- Oscar _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/DZZRL6IA62CTIKIQQZNG756Y25CJSE2N/ Code of Conduct: http://python.org/psf/codeofconduct/
