[Python-Dev] A new dictionary implementation (original) (raw)

Michael Foord fuzzyman at voidspace.org.uk
Thu Feb 2 18:03:32 CET 2012

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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