class - Python: differences among __setitem__ ; setattr ; set -

simple explanations examples 3 of them cannot interchanged.

def __setitem__(self,**k):         #self.val=k         key in k:             self.val.setdefault(key,[]).extend(v v in k[key]) 

can above step done in iterations setattr(obj,val[,can optional stuff come here??])

why not create our own style , private methods?

def _add(self,**k):     if isinstance(self, cclass):         key in k:             self.val.setdefault(key,[]).extend(v v in k[key]) 

q: class's scope allows these private methods accessed , used?

__setitem__ can used setting one item:

def __setitem__(self, key, value):     self.val.setdefault(key,[]).append(value) 

if prefer extend @ once 1 call, can build dict's .update() method takes iterable and/or keyword arguments:

def update(self, it, **k):     key, val in it:         self.val.setdefault(key,[]).extend(v v in val)     key, val in k.iteritems():         self.val.setdefault(key,[]).extend(v v in val)