Functions: Global and Local Scope (Livehacking Screenplay)¶

Undefined Variable
Local Variable
Global Variable
Local and Global Variable With Same Name
Assignment to Global Variable

Undefined Variable ¶

>>> def f():
...     print(x)
...
>>> f()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in f
NameError: name 'x' is not defined

Local Variable ¶

>>> def f():
...     x = 1
...     print(x)
...
>>> f()
1

Discuss: x ist not auomatically in global scope (like: e.g. Javascript)

Global Variable ¶

>>> def g():
...     print(globvar)
...
>>> globvar = 42
>>> g()
42

Local and Global Variable With Same Name ¶

code/30-local-global-same-name.py¶

x = 666

def f():
    x = 1
    print('local:', x)

f()
print('global:', x)

$ python code/30-local-global-same-name.py
local: 1
global: 666

Assignment to Global Variable ¶

How do I assign to a global variable then, if assignment creates a variable in local scope? ⟶ global keyword

code/40-global-assignment.py¶

x = 666

def f():
    global x
    x = 1
    print('assigned global:', x)

f()
print('global:', x)

$ python code/40-global-assignment.py
assigned global: 1
global: 1