[Tutor] Python __del__ method

[Jia Yue Kee]

Hi All,

I am new to Python and I came across the Python __del__ method the other day and I have some doubts on the output of the following code.

So, the snippet code goes something like this:

class Robot():

    def __init__(self, name):
        print(name + " has been created!")

    def __del__(self):
        print ("Robot has been destroyed")


if __name__ == "__main__":
    x = Robot("Tik-Tok")
    y = Robot("Jenkins")
    z = x
    z
    x
    del x
    del z
    del y

Case 1: If I were to run the code in  "Script Mode", the following output will be obtained:

Tik-Tok has been created!
Jenkins has been created!
Robot has been destroyed
Robot has been destroyed

Case 2: If I were to run the code in "Interactive Mode", the following output will be obtained:

>>> x = Robot("Tik-Tok")
Tik-Tok has been created!
>>> y = Robot("Jenkins")
Jenkins has been created!
>>> z = x
>>> z
<__main__.Robot object at 0x02D7E910>
>>> x
<__main__.Robot object at 0x02D7E910>
>>> del x
>>> del z
>>> del y
Robot has been destroyed

My question being why is that "Robot has been destroyed" is only printed once in Case 2 (interactive mode) while it is printed out twice in Case 1 (script mode)?
I did some study on garbage collection and based on my understanding, after the del x and del z statements, the refcount to the Robot object should reach zero and subsequently triggers the __del__ method right?
I am hoping someone could provide me a clearer picture on the doubts I have in mind.

Thanks and Regards,
JY