Scope

Writing Functions in Python

Shayne Miel

Software Architect @ Duo Security

Names

Names

Scope

Scope

Scope

x = 7
y = 200
print(x)

7

def foo():
    x = 42
    print(x)
    print(y)

foo()

42
200

print(x)

7

Scope

Scope

Scope

Scope

Scope

The global keyword

x = 7

def foo():
  x = 42
  print(x)

foo()

42

print(x)

7

x = 7

def foo():
  global x
  x = 42
  print(x)

foo()

42

print(x)

42

The nonlocal keyword

def foo():
  x = 10

  def bar():
    x = 200
    print(x)

  bar()
  print(x)

foo()

200
10

def foo():
  x = 10

  def bar():
    nonlocal x
    x = 200
    print(x)

  bar()
  print(x)

foo()

200
200

Let's practice!

Writing Functions in Python