[Python-Dev] Must objects with __enter__/__exit__ also supply __context__?

[Phillip J. Eby]

At 11:29 PM 4/25/2006 -0400, Phillip J. Eby wrote:
>See, if @contextfactory functions return a thing *with* a __context__
>method, how is that usable with "with"?  It isn't, unless the thing also
>happens to have __enter__/__exit__ methods.  This was the hole in the
>documentation that caused Nick to seek to revisit the decorator name in the
>first place.

Argh.  I seem to be tongue-tied this evening.  What I mean is, if 
@contextfactory functions' return value is usable as a "with" expression, 
that means it must have a __context__ method.  But, if you are using 
@contextfactory to *define* a __context__ method, the return value should 
clearly have __enter__ and __exit__ methods.

What this means is that if we describe the one method and the two methods 
as independent things, there is no *single* name we can use to describe the 
return value of a @contextfactory function.  It's a wave and a particle, so 
we either have to start talking about "wavicles" or have some detailed 
explanation of why @contextfactory function return values are both waves 
and particles at the same time.

However, if we say that particles are a kind of wave, and have all the same 
features as waves but just add a few others, then we can simply say 
@contextfactory functions return particles, and the waviness is implied, 
and all is right in the world.  At least, until AMK comes along and asks 
why you can't separate the particleness from the waveness, which was what 
started this whole thing in the first place...  :)