如何使用 __getitem__ 和 __iter__ 并从字典中返回值?

问题描述

我有一个带有字典的对象，我想通过 __getitem__ 访问该对象并对其进行迭代(仅值，键无关紧要)，但不知道该怎么做.p>

例如:

Python 2.5.2 (r252:60911, Jul 22, 2009, 15:33:10)>>>类库(对象):... def __init__(self):... self.books = {'title':对象，'title2':对象，'title3':对象，}... def __getitem__(self, i):...返回 self.books[i]...>>>图书馆=图书馆()>>>图书馆['标题']<输入对象">>>>图书馆借书:... 打印书...回溯(最近一次通话最后):<module> 中的文件<stdin>"第 1 行文件<stdin>"，第 5 行，在 __getitem__ 中关键错误:0>>>

我如何告诉它为字典中的每个项目简单地返回 object (键无关紧要)?

解决方案

def __iter__(self): return self.books.itervalues()

I have an object with a dictionary that I want to access via __getitem__ as well as iterate over (values only, keys don't matter) but am not sure how to do it.

For example:

Python 2.5.2 (r252:60911, Jul 22 2009, 15:33:10) 
>>> class Library(object):
...   def __init__(self):
...     self.books = { 'title' : object, 'title2' : object, 'title3' : object, }
...   def __getitem__(self, i):
...     return self.books[i]
... 
>>> library = Library()
>>> library['title']
<type 'object'>
>>> for book in library:
...   print book
... 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 5, in __getitem__
KeyError: 0
>>> 

How do I tell it to simply return the object for each item in the dictionary (the key doesn't matter) ?

解决方案

def __iter__(self): return self.books.itervalues()