# -*- coding: utf-8 -*-

class itemList:
    def __init__(self, observer):
        self.data = []
        self.observer = observer

    def __len__(self):
        return len(self.data)

    def __getitem__(self, idx):
        return self.data[idx]

    def __setitem__(self, idx, item):
        self.data[idx] = item

    def append(self, item):
        item.observer = self
        self.data.append(item)
        self.observer.notifyChange(item)

    def notifyChange(self, sender):
        self.observer.notifyChange(sender)

    def __add__(self, item):
        self.append(item)
        return self

    def __iter__(self):
        return self.data.__iter__()