On 4/28/2012 2:09 PM, laymanzh...@gmail.com wrote:
In my understanding, there is no directly relation between mutable
and hashable in Python. Any class with __hash__ function is
"hashable".
According the wiki: http://en.wikipedia.org/wiki/Immutable_object
In object-oriented and functional programming, an immutable object is
an object whose state cannot be modified after it is created.[1] This
is in contrast to a mutable object, which can be modified after it is
created.
We surely can define __hash__ function in user-define class and the
instance of that class can be changed thus mutable.
The default hash is based on the immutable value of an object. If you
base a custom hash on values that do change, it is not useful as a dict key.
--
Terry Jan Reedy
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