[Python-Dev] PEP 447: add type.locallookup (original) (raw)

Antoine Pitrou solipsis at pitrou.net
Mon Sep 9 19:49:59 CEST 2013

On Mon, 09 Sep 2013 09:05:57 -0700 Ethan Furman <ethan at stoneleaf.us> wrote:

On 09/09/2013 08:43 AM, Mark Shannon wrote: > I would like time to investigate this further, but at the moment I think it will either make attribute lookup poorly > defined or slow. > > Of the top of my head, the problem as a I see it is basically this: > Currently, type.getattribute() is a fixed point in the lookup of attributes. > The proposal means that a fixed point is not reached until the cls parameter of type.getattribute() is either object > or type, > otherwise type.getattribute() and type.locallookup must bounce back and forth. > > This will slow down every attribute lookup for what is a fairly obscure use case.

Looks like there's a patch we can try at http://bugs.python.org/issue18181. Here are Ronald's last timings:

Thanks but can you run a benchmark that actually exercises the feature? (I don't know enough about it to know what that would be, but I suppose it has to do with lookups on classes, rather than on instances)

Regards

Antoine.

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