[Python-ideas] PEP 4XX: Adding sys.implementation

[Eric Snow]

On Sat, Apr 28, 2012 at 12:22 AM, Chris Rebert <pyideas at rebertia.com> wrote:
> On Fri, Apr 27, 2012 at 11:06 PM, Eric Snow <ericsnowcurrently at gmail.com> wrote:
>>
>> * ``sys.implementation`` as a proper namespace rather than a dict.  It
>>  would be it's own module or an instance of a concrete class.
>
> So, what's the justification for it being a dict rather than an object
> with attributes? The PEP merely (sensibly) concludes that it cannot be
> considered a sequence.

At this point I'm not aware of the strong justifications either way.
However, sys.implementation is currently intended as a simple
collection of variables.  A dict reflects that.

One obvious concern is that if we start off with a dict we're binding
ourselves to that interface.  If we later want concrete class with
dotted lookup, we'd be looking at backwards-incompatibility.  This is
the part of the PEP that still needs more serious thought.

> Relatedly, I find the PEP's use of the term "namespace" in reference
> to a dict to be somewhat confusing.

In my mind a mapping is a namespace.  I don't have a problem changing
that to mitigate any confusion.  Thanks for the feedback.

-eric