class Gui(): var = None def refreshStats(args): print(str(var)) clas = Gui() clas.refreshStats() Trace
File "sample.py", line 5, in refreshStats print(str(var)) NameError: name 'var' is not defined. Why?
3 Answers
If you want your variables to be visible within the scope of your class functions, pass self into every class function and use your class variables as self.var such as this:
class Gui(): var = None def refreshStats(self, args): print(str(self.var)) clas = Gui() clas.refreshStats() If you want to use this as an instance variable (only for this instance of the class) as opposed to a class variable (shared across all instances of the class) you should be declaring it in the __init__ function:
class Gui(): def __init__(self): self.var = None def refreshStats(self, args): print(str(self.var)) clas = Gui() clas.refreshStats() 4 Comments
OneCricketeer
And what if the class variable was intentional?
ClydeTheGhost
You also should be initializing your class variables in an init function. see edits
OneCricketeer
That's called an instance variable, not a class variable
ClydeTheGhost
Quite right, I hope my edits have clarified things
make method inside class either classmethod or instance method then you can access all class instance property or varable inside method if method is instance method or if class method then class property you can access inside method
class A(): a = 0 def aa(self): """instance method""" print self.a @classmethod def bb(cls): """class method""" print cls.a 
Comments
var is not defined in the scope of your refreshStats() function, as it is a class variable.
As such, if you want to access it, you can do Gui.var.
2 Comments
chepner
This is basically just rewording the error message without explaining why
var is not defined.
vara class attribute belonging to theGuiclass, so you'd have to access it asGui.var.selfparameter onrefreshStats, by the way (unless you intendargsto be the class)