>> 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.
Thanks a lot! -- Psss, psss, put it down! - http://www.cafepress.com/putitdown -- http://mail.python.org/mailman/listinfo/python-list
