[Python-ideas] Collect **kw arguments as an ordered dictionary

Raymond Hettinger python at rcn.com
Sat Apr 18 00:09:51 CEST 2009


[Michael Foord]
> It would be nice if **kw arguments collected in a function / method signature
> were collected as an ordered dictionary rather  than ordinary dictionary.

I think that would be nice, but until ordered dicts get a C implementation,
it might greatly impair performance.


> Main use case, currently (I believe) the odict constructor doesn't guarantee 
> to preserve ordering if created with keyword arguments: 

That is correct.  And so noted in the docs:

     http://docs.python.org/dev/library/collections.html#ordereddict-objects


> My use case - I'd like to preserve the ordering to reproduce exactly the 
> order of arguments for the Mock module representation of the objects 
> are used. Because the order of iterating over arguments isn't the same 
> as they are passed in representations can't be compared in tests 
> reliably across Python versions / implementations.

Sounds reasonable.


Raymond
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