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- >> plementation? > > <devil's_advocate> One option is to create a new "frozen list" type, a` > la frozen sets.
doesn't frozenset make a copy? > People who argue that "frozen list" is not needed because we already > have the tuple type, while simultaneously arguing that tuples shouldn't > grow list methods because they are conceptually different from lists > will be bludgeoned to death with a paradox. http://www.python.org/peps/pep-0351.html This PEP describes a simple protocol for requesting a frozen, immutable copy of a mutable object. It also defines a new built-in function which uses this protocol to provide an immutable copy on any cooperating object. ... Here are some code samples which show the intended semantics class xset(set): def __freeze__(self): return frozenset(self) class xlist(list): def __freeze__(self): return tuple(self) ... </F> -- http://mail.python.org/mailman/listinfo/python-list