[Python-ideas] A Protocol for Making an Object Immutable

[Greg Ewing]

Eric Snow wrote:
> So, is being hashable necessarily
> tied to being immutable?

It's tied to immutability of those aspects involved in
equality comparison. If a type is to behave predictably
when used as a dict key, then two instances that compare
equal must always compare equal, and the converse.
Attributes that don't affect equality comparison are
free to change, however.

-- 
Greg