[Python-Dev] Why are contexts also managers? (was r45544 - peps/trunk/pep-0343.txt)
Phillip J. Eby
pje at telecommunity.com
Tue Apr 18 21:37:37 CEST 2006
At 04:18 PM 4/18/2006 -0400, A.M. Kuchling wrote:
>On Tue, Apr 18, 2006 at 08:55:18PM +0200, phillip.eby wrote:
> > Modified:
> > peps/trunk/pep-0343.txt
> > + "context manager" then encompasses all objects with a __context__()
> > + method that returns a context object. (This means that all contexts
> > + are context managers, but not all context managers are contexts).
>This change reminds of another question I had about the parenthetical
>statement: all contexts are context managers (= 'has a __context__'
>method). Why? The context object isn't necessarily available to the
>Python programmer, so they can't write:
>with context_mgr as context:
> with context: # uses the same context
>Why do contexts need to have a __context__() method?
I was going to say, "so they can be context managers", but I suppose you
have a point. There is no need for a context to have a __context__ method,
unless it is also a context manager. Ugh.
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