Say I have something like:

class name:
.....def __init__(self,a):
..........self.a = a
..........self.b = [0 for i in range(a)

Now lets say I wrote a python program that has a main function that prompts the user for a set of numbers in the range(a). How do I get that set of numbers in the variable list self.b without defining another method the in the name class to do so?

well you could simply do this:

class Name:
    def __init__( self, a, listOfValues ):
        self.a = a
        self.b = [ i for i in listOfValues ]

def main():
    a = 5
    # Generate the userInput list
    #....
   
    # and create the new object by passing the range and the list to the constructor
    n = Name( a, userInput )

main()

Hope this helps :)