Class NameError: name 'var' is not defined

Question

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?

Answer 1

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()