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

Tue Apr 18 22:18:29 CEST 2006

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?
--amk