I want to write a custom class that behaves like dict - so, I am inheriting from dict.
My question, though, is: Do I need to create a private dict member in my __init__() method?. I don't see the point of this, since I already have the dict behavior if I simply inherit from dict.
谁能指出为什么大多数继承片段看起来像下面的片段？
class CustomDictOne(dict):
def __init__(self):
self._mydict = {}
# other methods follow
而不是简单的...
class CustomDictTwo(dict):
def __init__(self):
# initialize my other stuff here ...
# other methods follow
实际上，我认为我怀疑问题的答案是，用户无法直接访问您的字典（即他们必须使用您提供的访问方法）。
However, what about the array access operator []? How would one implement that? So far, I have not seen an example that shows how to override the [] operator.
So if a [] access function is not provided in the custom class, the inherited base methods will be operating on a different dictionary?
我尝试了以下代码段来测试对Python继承的理解：
class myDict(dict):
def __init__(self):
self._dict = {}
def add(self, id, val):
self._dict[id] = val
md = myDict()
md.add('id', 123)
print md[id]
我收到以下错误：
KeyError：<内置函数ID>
上面的代码有什么问题？
How do I correct the class myDict so that I can write code like this?
md = myDict()
md['id'] = 123
[编辑]
我已经编辑了上面的代码示例，以摆脱在离开办公桌前犯下的愚蠢错误。这是一个错字（我应该从错误消息中发现它）。
最佳答案
Check the documentation on emulating container types. In your case, the first parameter to add should be self.
