[Python-ideas] An identity dict

[Michael]

+1 - this has been useful to me in other languages.

(apologies for top-post, sent from phone.)

Michael Foord


--
http://www.ironpythoninaction.com

On 30 May 2010, at 04:27, Benjamin Peterson <benjamin at python.org> wrote:

> In the spirit of collections.OrderedDict and  
> collections.defaultdict, I'd like
> to propose collections.identitydict. It would function just like a  
> normal
> dictionary, but ignore hash values and comparison operators and  
> merely lookup
> keys based on the key's id().
>
> This dict is very useful for keep track of objects that should not  
> be compared
> by normal comparison methods. For example, I would use an  
> identitydict to hold
> weak references that would otherwise fallback to their referant  
> object's hash.
>
> An advantage of formalizing this in collections would be to enable  
> other Python
> implementations like PyPy, where id() is expensive, to provide an  
> optimized
> identitydict.
>
> Regards,
> Benjamin
>
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