在 python 类上重载 __dict__()
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Overloading __dict__() on python class
提问by code base 5000
I have a class where I want to get the object back as a dictionary, so I implemented this in the __dict__(). Is this correct?
我有一个类，我想将对象作为字典取回，所以我在__dict__(). 这样对吗？
I figured once I did that, I could then use the dict(custom object), and get back the object as a dictionary, but that does not work.
我想一旦我这样做了，我就可以使用dict（自定义对象），并将对象作为字典取回，但这不起作用。
Should you overload __dict__()? How can you make it so a custom object can be converted to a dictionary using dict()?
你应该超载__dict__()吗？您如何才能使用 将自定义对象转换为字典dict()？
采纳答案by Martijn Pieters
__dict__is nota special method on Python objects. It is used for the attribute dictionary; dict()never uses it.
__dict__是不是对Python对象的特殊方法。用于属性字典；dict()从不使用它。
Instead, you could support iteration; when dict()is passed an iterablethat produces key-value pairs, a new dictionary object with those key-value pairs is produced.
相反，您可以支持迭代；当dict()传递一个产生键值对的可迭代对象时，会产生一个带有这些键值对的新字典对象。
You can provide an iterable by implementing a __iter__method, which should return an iterator. Implementing that method as a generator function suffices:
您可以通过实现一个__iter__方法来提供一个迭代器，该方法应该返回一个迭代器。将该方法实现为生成器函数就足够了：
class Foo(object):
def __init__(self, *values):
self.some_sequence = values
def __iter__(self):
for key in self.some_sequence:
yield (key, 'Value for {}'.format(key))
Demo:
演示：
>>> class Foo(object):
... def __init__(self, *values):
... self.some_sequence = values
... def __iter__(self):
... for key in self.some_sequence:
... yield (key, 'Value for {}'.format(key))
...
>>> f = Foo('bar', 'baz', 'eggs', 'ham')
>>> dict(f)
{'baz': 'Value for baz', 'eggs': 'Value for eggs', 'bar': 'Value for bar', 'ham': 'Value for ham'}
You could also subclass dict, or implement the Mapping abstract class, and dict()would recognize either and copy keys and values over to a new dictionary object. This is a little more work, but may be worth it if you want your custom class to act like a mapping everywhere else too.
您还可以子类化dict或实现Mapping 抽象类，并且dict()可以识别其中之一并将键和值复制到新的字典对象中。这需要做更多的工作，但如果您希望自定义类也像其他任何地方的映射一样，那么这可能是值得的。
回答by letitbee
No. __dict__is a method used for introspection - it returns object attributes. What you want is a brand new method, call it as_dict, for example - that's the convention. The thing to understand here is that dictobjects don't need to be necessarily created with dictconstructor.
No.__dict__是一种用于内省的方法 - 它返回对象属性。您想要的是一种全新的方法，as_dict例如将其称为－ 这是惯例。这里要理解的是，dict对象不一定需要用dict构造函数创建。
