[Python-Dev] Why are contexts also managers? (wasr45544 -peps/trunk/pep-0343.txt) (original) (raw)

Terry Reedy tjreedy at udel.edu
Sun Apr 23 01:41:00 CEST 2006

"Nick Coghlan" <ncoghlan at gmail.com> wrote in message news:444A20D9.5010607 at gmail.com...

As Phillip pointed out, we need input from people that haven't been intimately involved in the PEP 343 discussions

OK, here is my attempt to cut the knot.

To me, 'context' and 'context manager' can be seen as near synonyms; either could be used to describe the thing that 'governs' the block execution. I (and some other others) prefer the shorter term; yet I can see how someone (you, at least) could prefer the longer, more explicit term.

To me, the thing after 'with' that makes the whatever for the block is DEFINITELY not a 'context'; trying to twist context to mean that is a brain twister. Calling it 'context manager' is possible if one interpretes 'manager' instead as a hands-off manager who appoints a foreman to do the actual work and then departs. But the term is ambiguous as this discussion has shown.

So I propose that the context maker be called just that: 'context maker'. That should pretty clearly not be the context that manages the block execution.

An additional source of confusion is that we can name a function got several reasons; among them one is what it is, another is what it returns. For instance, a generic generator for-loop could be written as either of for item in generator_function(): for item in generator(): In context, I think the second reads better, as long as it is clear that the function name 'generator' refers what it returns and not what it is.

Similar, a context_maker function could be named any of 'context_maker', 'context_manager', or 'context', with the latter two referring to the return value. In the context of 'with ____ as name:', either of the latter two reads better to me.

I would call the decorator @contextmaker since that is what it turns the decorated function into.

Well, I hope this slightly different viewpoint is at least a bit helpful.

Terry Jan Reedy

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