python basic explanation needed

Question

Can someone please explain me the following code TickGenerator inherit from object and methods of Observer, why do we need both observer.init?

class TickGenerator(Observer):
 def __init__(self):
 Observer.__init__(self)
 self.price = 1000

• Paulo Scardine: the canonical way to call the parent constructor is using the super() builtin.

Answer 1

I guess you came from a language where the parent class constructor is automatically called.

In Python, if you override the __init__ method, the parent class constructor will not be called unless you call it explicitly.

Until Python 3, it used to be called as:

def __init__(self, *args, **kwargs):
 super(TickGenerator, self).__init__(*args, **kwargs) 

The new [super()][1] syntax (PEP-3135) is just:

def __init__(self, *args, **kwargs):
 super().method(*args, **kwargs)

• 0x90: Observer.__init__(self) isn't it a calling to the super class constructor ?
• Paulo Scardine: I guess the OP question is why he has to call Observer.__init__(self) at all, and it makes sense if he is versed in a computer language where the parent constructor call is implicit.

Answer 2

Because programmer needs Observer class __init__ to be done in addition to what is being done in the current class's (TickGenerator) __init__.

This Stackoverflow answer will help you understand more.

Answer 3

If you don't call Observer.init as below:

class TickGenerator(Observer):
 def __init__(self):
 self.price = 1000

It means you override the TickGenerator.init method and Observer.init will not be called automaticlly.