object 和 __init__ 方法

Question

I am learning Python and I heard all functions are objects. And classes are objects too, if I am not mistaken. Then methods within a class must be objects.

Then I wonder, within __init__ method, which is an object, are the attributes objects, too? Objects within an object?

There is a phrase 'Everything is an object'. And my impression is that anything that holds a memory space is an object. What I don't quite grasp is to what extent the phrase 'everything is an object' applies. I wonder if it applies even to variables within __init__ method.

Answer 1

Yes, it's quite similar to Java. Every Python variable hides a pointer to the right location of memory which contains the actual data. There are only four primitive types in Python: integers, floats, booleans and strings; anything else is an ADT. The keyword self is the same of this in Java or C++, in other words the self-reference. Using self , you can invoke another method inside the class or access to an attribute. Syntax like self.var = 1 can also creates a new attribute (if it doesn't exist yet) with name "var", type "int" and value 1.