[Python-Dev] sys.implementation (original) (raw)

Eric Snow ericsnowcurrently at gmail.com
Sat May 12 19:50:10 CEST 2012

On Sat, May 12, 2012 at 6:04 AM, Nick Coghlan <ncoghlan at gmail.com> wrote:

On Sat, May 12, 2012 at 12:40 PM, Eric Snow <ericsnowcurrently at gmail.com> wrote:

If anyone has strong feelings for item-access over attribute-access, please elaborate.  I'm just not seeing it as that important and would rather finish up the PEP as simply as possible. I object to adding a new type to the stdlib just for this PEP.

And I agree with you. :) The only constraint is that it be an object with attribute access. That could be a named tuple, a module, an uninstantiated class, or whatever. A new type is not needed. If it's iterable or not is irrelevant with regards to the PEP. For the implementation I'd like it to have a good repr too, but even that's not part of the proposal.

I've got the latest version of the PEP up now. It pares down the type discussion and eliminates "metadata". I figure it's good enough for what we need, and I've put adequate(?) warning that people shouldn't mess with it (consenting adults, etc.). Let me know what you think.

Since iterating over the keys is significantly more useful than iterating over the values, that suggests a dictionary as the most appropriate type.

If someone really wants a quick way to get dotted access to the contents of dictionary:

data = dict(a=1, b=2, c=3) ns = type('', (), data) ns.a 1 ns.b 2 ns.c 3

That's pretty cool. As a counter example, given a normal (dict-based) object you can use vars() to turn it into a dict:

data = SomeClass(a=1, b=2, c=3) ns = vars(data) ns['a'] 1 ns['b'] 2 ns['c'] 3

I'll grant that it doesn't work for some objects (like named tuples), but for sys.implementation I don't think it matters either way.

-eric

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