Ex43 help: Passing variable between classes

Python
#1

Hello, I’m trying to add an HP counter that increases/decreases depending on the choices being made in the game. I’m struggling though passing that value between classes. The following works to pass a variable from Parent to Child classes:

class Parent(object):
var1 = 1

class Child(Parent):
def fun(self):
var2 = Parent.var1 + 1
return var2

p = Parent()
a = p.var1
print(f’{a}’)

c = Child()
b = c.fun()
print(f’{b}’)

However, when you add a third class it gives an error:

class Grandkid(Child):
def fun2(self):
var3=Child.var2+1
return self.var3

c = Grandkid()
d = c.fun2()
print(f’{d}’)

Any help would be greatly appreciated.

#2

I’ll give you a quick hint, don’t have much time: Read up on

  • class attributes
  • instance attributes
  • local variables

If you don’t find the answer, ask again and I’ll explain what’s going on. :slight_smile:

#3

Hmm trying that helped me identify the instance attributes, but I’m struggling with it. Any further hints would be helpful!

#4

Which of the three types of variables is var2 and how are you trying to access it in Grandkid.fun?

By the way, you don’t need an f-string to print a variable. You can simply do print(var).

#5

I believe var1 is a class variable, but var2 is an instance variable - but I’m trying to access both as a class variable?

#6

Close. var2 is actually a local variable that exists only during the execution of Child.fun.

You could make it an instance attribute of c that persists as long as c exists by defining it on self:

self.var2 = Parent.var1 + 1

Then you could access it as c.var2.

If you wanted it to be a class attribute you’d have to define it on Child:

Child.var2 = Parent.var1 + 1

Then you could later access it as Child.var2.

1 Like
#7

Ah ok I understand now - thank you so much for your help!