Python, List of Children-CodePudding

I want to generate a parent/child datastructure in Python 3.8.10. [GCC 9.3.0] on linux The code is as simple as:

class Member(object):
    name = "xxx"
    parent = None
    children = []
    
    def __init__(self, name):
        object.__init__(self)
        self.name = name
    
    def setParent(self,p):
        self.parent = p
        
    def addChild(self,ch):
        self.children.append(ch)
        ch.setParent(self)
        
    def myRelatives(self):
        str = "I am {0}, my parent is {1} my children are:".format(self.name,self.parent.name if self.parent is not None else "--")
        print(str)

        for ch in self.children:
            print("   {0}".format(ch.name))
       

if __name__ == '__main__':
    A = Member("A")
    B = Member("B")
    C = Member("C")
    D = Member("D")
    
    A.addChild(B)
    B.addChild(C)
    C.addChild(D)
    
    A.myRelatives()
    B.myRelatives()
    C.myRelatives()
    D.myRelatives()

I have expected:

I am A, my parent is -- my children are:
   B
I am B, my parent is A my children are:
   C
I am C, my parent is B my children are:
   D
I am D, my parent is C my children are:

However my output is:

I am A, my parent is -- my children are:
   B
   C
   D
I am B, my parent is A my children are:
   B
   C
   D
I am C, my parent is B my children are:
   B
   C
   D
I am D, my parent is C my children are:
   B
   C
   D

It seems the 'self.children' is used as same variable in all instances. Why and how to fix?

Thanks, Bernd

CodePudding user response：

You need to set the attributes name, parent, and children in the __init__ function, so e.g. like so:

    def __init__(self, name):
        super().__init__(self)
        self.name = name
        self.parent = None
        self.children = list()

Then it should work.

EDIT: Added improvement suggested by @chepner.