On 10/31/05, Antoine Pitrou <[EMAIL PROTECTED]> wrote: > > > It allows everything in Python to be both mutable and hashable, > > I don't understand, since it's already the case. Any user-defined object > is at the same time mutable and hashable.
By default, user-defined objects are equal iff they are the same object, regardless of their content. This makes mutability a non-issue. If you want to allow different objects be equal you need to implement a consistent equality operator (commutative, etc), a consistent hash function and ensure that any attributes affecting equality or hash value are immutable. If you fail to meet any of these requirements and put such objects in dictionaries or sets it will result in undefined behavior that may change between Python versions and implementations. Oren _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
