Python Variables Scope

• No block-level scope.
• Initializing a variable in a if, for branch will make the variable available for the rest of the function.

global and nonlocal

global

Used to say that an identifier name used in the current code block should be interpreted as global. It would be impossible to assign a global variable without global E.g.:

a = 1
def foo():
    global a
    a += 1

foo()
print(a)

nonlocal

Used to say that an identifier names used in the current code block should be interpreted as the one in the nearest enclosing scope, i.e. non local and non global. E.g.:

def foo():
    a = 1
    def bar():
        nonlocal a
        a += 1
    bar()

foo()