从类方法创建新的类实例

问题描述

我希望能够通过在已实例化的对象上调用方法来创建对象的新实例。例如，我有一个对象：

I want to be able to create a new instance of an object by calling a method on an already instantiated object. For example, I have the object:

organism = Organism（）

我希望能够调用 organism.reproduce（）并具有两个Organism类型的对象。此时我的方法如下：

I want to be able to call organism.reproduce() and have two objects of type Organism. My method at this point looks like this:

class Organism(object):
    def reproduce():
        organism = Organism()

我很确定它不起作用（I'我甚至还不确定如何测试它。我在）。那么，如何使我的对象创建自己可访问的副本，就像我创建的第一个对象一样（使用 organism = Organism（））？

and I'm pretty sure it doesn't work (I'm not really even sure how to test it. I tried the gc method in this post). So how can I make my object create a copy of itself that's accessible just like the first object I created (with organism = Organism())?

推荐答案

class Organism(object):
    def reproduce(self):
        #use self here to customize the new organism ...
        return Organism()

另一种选择-如果在方法中未使用实例（ self ）：

Another option -- if the instance (self) isn't used within the method:

class Organism(object):
    @classmethod
    def reproduce(cls):
        return cls()

这可以确保生物产生更多的生物，（从生物衍生的假想的Borg产生更多的Borg）。

This makes sure that Organisms produce more Organisms and (hypothetical Borgs which are derived from Organisms produce more Borgs).

附带好处不需要使用 self 的原因在于，除了可以从实例调用之外，现在还可以直接从类中调用它：

A side benefit of not needing to use self is that this can now be called from the class directly in addition to being able to be called from an instance:

new_organism0 = Organism.reproduce()  # Creates a new organism
new_organism1 = new_organism0.reproduce()  # Also creates a new organism

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最后，如果实例（ self ）和类（ Organism 或子类（如果从子类调用）：

---

Finally, if both the instance (self) and the class (Organism or subclasses if called from a subclass) are used within the method:

class Organism(object):
    def reproduce(self):
        #use self here to customize the new organism ...
        return self.__class__()  # same as cls = type(self); return cls()





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在每种情况下，您d将其用作：

---

In each case, you'd use it as:

organism = Organism()
new_organism = organism.reproduce()

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