On Wed, Dec 10, 2008 at 11:53 PM, Daniel Fetchinson <[EMAIL PROTECTED]> wrote: > I just found out that if I want to have a custom dict it's not enough > to overload __getitem__, __setitem__ and __delitem__ because, for > example, pop and clear don't call __delitem__. I.e. an instance of the > following will not print 'deleted' upon instance.pop( 'key' ): > > class mydict( dict ): > def __setitem__( self, key, value ): > print 'set' > super( mydict, self ).__setitem__( key, value ) > def __getitem__( self, key ): > print 'get' > super( mydict, self ).__getitem__( key ) > def __delitem__( self, key ): > print 'deleted' > super( mydict, self ).__delitem__( key ) > > Why is this?
For optimization purposes essentially, so that the built-in dict can be as fast as possible as it is used pervasively in Python. > what other methods do I have to overload so that > I get what I expect for all dict operations? You might consider just subclassing UserDict.DictMixin instead: http://docs.python.org/library/userdict.html#UserDict.DictMixin It implements the complete dict interface all in terms of provided __getitem__(), __setitem__(), __delitem__(), and keys() methods. Cheers, Chris -- Follow the path of the Iguana... http://rebertia.com > > Cheers, > Daniel > -- http://mail.python.org/mailman/listinfo/python-list
