I actually did that in the project I made Combi for. I had a bunch of perm spaces that signified certain configurations (can't get more specific, sorry) and I wanted to find the best configuration in each space. So I had a dict from each space to the best configuration in that space.

On Tue, Nov 18, 2014 at 1:05 AM, Steven D'Aprano <steve@pearwood.info> wrote:
On Mon, Nov 17, 2014 at 09:57:55PM +0200, Ram Rachum wrote:
> Ah, I understand. I don't like it, though I'm not sure I can really express
> why. One reason is that this would mean that PermSpaces would be mutable,
> and thus not hashable and not usable as keys in dicts and sets.

I'm having trouble thinking of any reason to use a PermSpace as a dict
key or set element. Do you have a concrete example of doing so?

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