[Python-Dev] A new dictionary implementation

[Michael Foord]

On 02/02/2012 11:30, Chris Withers wrote:
> On 01/02/2012 17:50, Guido van Rossum wrote:
>> Another question: a common pattern is to use (immutable) class
>> variables as default values for instance variables, and only set the
>> instance variables once they need to be different. Does such a class
>> benefit from your improvement?
>
> A less common pattern, but which still needs to work, is where a 
> mutable class variable is deliberately store state across all 
> instances of a class...
>
Given that Mark's patch passes the Python test suite I'm sure basic 
patterns like this *work*, the question is which of them take advantage 
of the improved memory efficiency. In the case you mention I don't think 
it's an issue at all, because the class level attribute doesn't 
(generally) appear in instance dicts.

What's also common is where the class holds a *default* value for 
instances, which may be overridden by an instance attribute on *some* 
instances.

All the best,

Michael Foord

> Chris
>


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