Python继承:返回子类 [英] Python Inheritance : Return subclass
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问题描述
我在超类中有一个函数,该函数返回自身的新版本.我有一个继承于特定函数的超类的子类,但宁愿它返回该子类的新版本.我该如何编码,以便当从父级进行函数调用时,它返回父级的版本,但是从子级中调用时,它返回子级的新版本?
I have a function in a superclass that returns a new version of itself. I have a subclass of this super that inherits the particular function, but would rather it return a new version of the subclass. How do I code it so that when the function call is from the parent, it returns a version of the parent, but when it is called from the child, it returns a new version of the child?
推荐答案
如果new
不依赖self
,请使用类方法:
If new
does not depend on self
, use a classmethod:
class Parent(object):
@classmethod
def new(cls,*args,**kwargs):
return cls(*args,**kwargs)
class Child(Parent): pass
p=Parent()
p2=p.new()
assert isinstance(p2,Parent)
c=Child()
c2=c.new()
assert isinstance(c2,Child)
或者,如果new
确实依赖于self
,请使用type(self)
确定self
的类:
Or, if new
does depend on self
, use type(self)
to determine self
's class:
class Parent(object):
def new(self,*args,**kwargs):
# use `self` in some way to perhaps change `args` and/or `kwargs`
return type(self)(*args,**kwargs)
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