[Python-Dev] Why are contexts also managers? (was r45544 - peps/trunk/pep-0343.txt)
Nick Coghlan
ncoghlan at gmail.com
Thu Apr 20 13:49:43 CEST 2006
Phillip J. Eby wrote:
> At 11:41 PM 4/19/2006 +1000, Nick Coghlan wrote:
>> Given that naming though, I think contextlib.contextmanager should be
>> renamed
>> to contextlib.context.
>
> The name is actually correct under this terminology arrangement.
> @contextmanager *returns* a context manager.
That's like saying we should describe the result of calling a generator
function as a generator-iterable because it has an __iter__ method.
The longer name made sense when "context manager" was the term for the object
with __enter__ and __exit__ methods (the way I originally wrote it when
updating the PEP after the addition of the __context__ method).
While I agree that flipping the terminology the other way around makes sense,
it *also* flips the effect of calling a decorated generator function so that
what it returns is now appropriately termed a generator-context (since it
provides __enter__ and __exit__ methods directly).
These contexts are context managers only in the same sense that iterators are
also iterables. We shouldn't break the parallels between iterable-iterator and
context manager-context without a good reason - and so far I haven't heard one.
Cheers,
Nick.
--
Nick Coghlan | ncoghlan at gmail.com | Brisbane, Australia
---------------------------------------------------------------
http://www.boredomandlaziness.org
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