Is it necessary to call super().init() explicitly in python?

Question

I came from Java where we can avoid calling super class zero-argument constructor. The call to it is generated implicitly by the compiler.

I read this post about super() and now in question about is it really necessary to do something like this explicitly:

class A(object):
 def __init__(self):
   print("world")

class B(A):
 def __init__(self):
   print("hello")
   super().__init__() #Do we get some Undefined Behavior if we do not call it explicitly?

@Sayse The question is not about behavior of a particular python implementation. It is about legitimacy in general. — Some Name, Feb 01 '20 at 08:46
Yes, but the answer should become clear whether it prints or not — Sayse, Feb 01 '20 at 08:48
@Sayse It does! So generally it can be avoided... Which is not clear why they mentioned it explcitly — Some Name, Feb 01 '20 at 08:49
World does not get printed.. [example](https://ideone.com/O60xQl) — Sayse, Feb 01 '20 at 08:54
Omitting super init is not UB, just like omitting any other calls. Objects are well defined before init. — MisterMiyagi, Feb 01 '20 at 09:20

tripleee · Accepted Answer · 2020-02-01T09:22:25.560

If you override the __init__ method of the superclass, then the __init__ method of the subclass needs to explicitly call it if that is the intended behavior, yes.

Your mental model of __init__ is incorrect; it is not the constructor method, it is a hook which the constructor method calls to let you customize object initialization easily. (The actual constructor is called __new__ but you don't need to know this, and will probably never need to interact with it directly, let alone change it.)

Is it necessary to call super().__init__() explicitly in python?

1 Answers1

Is it necessary to call super().init() explicitly in python?