General question about Python design goals

Rocco Moretti roccomoretti at
Thu Dec 1 19:35:18 CET 2005

Fredrik Lundh wrote:
> Rocco Moretti wrote:
>>>>I'm sure Antoon wouldn't object if lists were to be allowed as
>>>>dictionary keys, which would eliminate the multiple castings for
>>>>that situation. I wouldn't, either.
>>>so what algorithm do you suggest for the new dictionary im-
>><devil's_advocate> One option is to create a new "frozen list" type, a`
>>la frozen sets.
> doesn't frozenset make a copy?

As does the current "cast as tuple" technique. (I'm certainly not 
advocating it, but ...) Certain implementations of "frozen list" could 
possibly do the list->frozenlist conversion without a copy. (e.g. by 
flipping an "immutable" bit)

>     This PEP describes a simple protocol for requesting a frozen,
>     immutable copy of a mutable object. 

Perhaps Barry has been borrowing Guido's time machine?

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