Difference between a=b=class_name(value) and a=class_name(value) b=class_name(value) in python [not duplicate]

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In the following code, if I use tree = parent = node(leaf_1) the tree and parent are always having the same print result; whereas, if I change that line to tree = node(leaf_1) and parent = node(leaf_1), then the tree and parent will not be the same.

class node(object):
    def __init__(self, value):
        self.value = value
        self.children = []
    def __repr__(self, level=0):
        ret = "\t"*level+repr(self.value)+"\n"
        for child in self.children:
            ret += child.__repr__(level+1)
        return ret
    def add(self, nod):
        self.children.append(node(nod))
leaf_1 = [1,4,3]
leaf_2 = [2,5,3]
leaf_3 = [4,4,3]

tree = parent = node(leaf_1) #### code 1
parent.add(leaf_2)
parent.add(leaf_3)
print(tree)
print(parent)

In above code, both print have the same output as follows:

output 1:
[1, 4, 3]
    [2, 5, 3]
    [4, 4, 3]

However, if I change tree = parent = node(leaf_1) to tree = node(leaf_1) and parent = node(leaf_1), output:

output 2:
[1, 4, 3]

[1, 4, 3]
    [2, 5, 3]
    [4, 4, 3]

My question:

why the tree = parent = node(leaf_1) and tree = node(leaf_1); parent = node(leaf_1) have different output?

Thanks in advance!

repr instance object class python
1 Answers

This tree = parent = node(leaf_1), creates a single node object and assigns it to tree and parent and this tree = node(leaf_1); parent = node(leaf_1) created two different node objects and assigns them to tree and parent respectively.

parent.add(leaf_2)
parent.add(leaf_3)

Here you are adding leaf_2 and leaf_3 only to parent. That may be the reason of output in second case.

user_144291850
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