how to declare uninitialized variable in class definition in python

Question

I come from a MATLAB background. When I create class definitions, I can instantiate "empty" variable names and then later assign values or objects to them. I.e.

---

classdef myclass < handle

    properties
        var1
        var2
    end 
end

a = myClass;
a.var1 = someOtherClassObject;

How do I do this in Python? I tried something like this:

class myClass:
def __init__(self):
    var1 
    var2

a = myClass()
a.var1 = someOtherClassObject()

But that's not correct. The main purpose is to build a definition of my class, like a structure, and then later go and instantiate the variables as needed.

And help would be appreciated.

Answer 1

You need to use self. to create variables for instances (objects)

I do not think you can have an uninitialized name in python, instead why not just initialize your instance variables to None ? Example -

class myClass:
    def __init__(self):
        self.var1 = None 
        self.var2 = None

You can later go and set them to whatever you want using -

a = myClass()
a.var1 = someOtherClassObject

If you need to define class variables (that are shared across instances) , you need to define them outside the __init__() method, directly inside the class as -

class myClass:
    var1 = None
    var2 = None
    def __init__(self):
        pass