[Python-Dev] Why are contexts also managers? (was r45544 - peps/trunk/pep-0343.txt) (original) (raw)

Paul Moore p.f.moore at gmail.com
Sat Apr 22 15:23:36 CEST 2006

On 4/22/06, Nick Coghlan <ncoghlan at gmail.com> wrote:

So I'm going to express my gratitude by asking you to read the same docs all over again in a few days time :)

No problem. Remind me if I forget...

I'll be making a pass through the docs (and PEP) this weekend using the definitions:

- a context manager is a thing with enter/exit methods (it sets up and tears down an execution context for a block of code) - the with statement delimits the block which is in an execution context - the with statement asks a context object for a context manager to set up and tear down an execution context when the block runs - context objects have a context method to produce context managers (hey, it isn't really that much worse than using the iter method to ask an iterable for an iterator. . .)

Sorry, but I don't really like this. I find the idea of a context manager, creating contexts, within which the block in a with statement runs, much more intuitive. As I said, the only issue I have with it is the dual use of the contextmanager decorator (and I think that's fundamental - there are 2 different things going on, and they should have different names).

But I'll do my best to put away my prejudices and read the new docs as they are written, when they come out.

If the terminology still breaks down with those slightly different definitions, we'll have to try to come up with a third option after the 2nd alpha. I'm really hoping my planned changes actually work out, because if they don't I'm out of ideas for how to make these concepts easier to grok. . .

Presumably, then, my proposal didn't make things clear to you?

I won't comment further on your proposal, as I want to avoid thinking about it before I read the docs...

Paul.

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