I thought rewriting __hash__ should be enough to avoid mutables problem but:
class H(set): def __hash__(self) return id(self) s=H() f=set() f.add(s) f.remove(s) the add succeeds the remove fails eventually not calling hash(s). Thanks for help Paolino ___________________________________ Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB http://mail.yahoo.it -- http://mail.python.org/mailman/listinfo/python-list