如何在类的成员函数中返回类实例?

问题描述

我想在类的成员函数中返回一个类实例，我的代码是:

I want to return a class instance in member function of a class, my code is:

class MyClass(object):
    def __init__(self, *args, **kwargs):
        [snippet]

    def func(self, *args, **kwargs):
        [snippet]
        return class_instnace_of_MyClass

if __name__ == '__main__':
    obj = MyClass(...)
    newobj = obj.func(...)  # type(newobj) is MyClass

我认为我可以在func()中调用__init__()，并返回MyClass的新实例，但是我认为这不是Python的方法.我该怎么办?谢谢！

I think I can call __init__() in func(), and return a new instance of MyClass, but I don't think it is a Pythonic way to do so. How should I do that? Thank you!

推荐答案

如果我没看错你的话，我觉得你应该使用@classmethod装饰器.像这样:

I feel like you should use the @classmethod decorator for this, if I'm reading your question right. Something like:

class myClass(object):

    def __int__(name):
        self.name = name

    @classmethod
    def from_fancy(cls, name):
        #do something with name, maybe make it
        #lowercase or something...
        return cls(name)

例如，在pandas包中，您可以通过执行pandas.DataFrame.from_csv(...)或pandas.DataFrame.from_json(...)之类的操作来创建DateFrame对象.这些方法都是返回DataFrame对象的类方法，该对象使用不同的初始数据集(csv文本文件或JSON文本文件)创建.

For example, in the pandas package you can create a DateFrame object by doing things like pandas.DataFrame.from_csv(...) or pandas.DataFrame.from_json(...). Each of those are class methods which return a DataFrame object, created with different initial data sets (csv text file or a JSON text file).

例如，您会这样称呼它:

For instance, you would call it like:

my_new_object = myClass.from_fancy("hello world")

@classmethod 此处

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