Are the attributes in a Python class shared or not? [duplicate]

Answer 1

In the both case, you replacing the self.name to a new value.

In the first case you're mutating the self.tricks list, mutating a list don't replace it. so during the whole execution you have a single list, being mutated.

In the second case, the line self.tricks=[name] is changing the list, creating a new list object.

You can easily introspect this like:

class mytest:
    name = "test1"
    tricks = list()
    print("tricks id during class definition is: {}".format(id(tricks)))

    def __init__(self, name):
        self.name = name
        print("self.tricks id at the beginning of __init__ is: {}".format(id(self.tricks)))
        self.tricks = [name]
        print("self.tricks id after being replaced is: {}".format(id(self.tricks)))
        print("but mytest.tricks id is still: {}".format(id(mytest.tricks)))
        self.tricks.append(name)

t1=mytest("hello world")
t2=mytest("bye world")

Giving:

tricks id during class definition is: 140547174832328
self.tricks id at the beginning of __init__ is: 140547174832328
self.tricks id after being replaced is: 140547174831432
but mytest.tricks id is still: 140547174832328
self.tricks id at the beginning of __init__ is: 140547174832328
self.tricks id after being replaced is: 140547174830600
but mytest.tricks id is still: 140547174832328