4.3. Namespace

4.3.1. Rationale

• Functions provide namespaces

• Only code inside that namespace can access it's locals

def run():
    a = 1
    print(a)


print(a)
# Traceback (most recent call last):
# NameError: name 'a' is not defined

run()
# 1

4.3.2. Functions Inside Function

• Functions inside function

def run():
    def a():
        print('A')

    def b():
        print('B')

4.3.3. Classes Inside Function

def run():
    class A:
        pass

    class B:
        pass

4.3.4. Variables, Functions and Classes Inside Function

def run():
    myvariable = 1

    def myfunction:
        pass

    class MyClass:
        pass

4.3.5. Execute

def run():
    def a():
        print('A')

    def b():
        print('B')

    a()
    b()


result = run()
# A
# B

print(result)
# None

4.3.6. Return

def run():
    def a():
        return 'A'

    def b():
        return 'B'

    return a(), b()


run()
# ('A', 'B')

run()()
# Traceback (most recent call last):
# TypeError: 'tuple' object is not callable

('A', 'B')()
# Traceback (most recent call last):
# TypeError: 'tuple' object is not callable

def run():
    def a():
        print('A')

    def b():
        print('B')

    return b


run()
# <function __main__.run.<locals>.b()>

run()()
# B

def run():
    def a():
        print('A')

    def b():
        print('B')

    return a, b


run()
# (<function __main__.run.<locals>.a()>,
#  <function __main__.run.<locals>.b()>)

run()()
# Traceback (most recent call last):
# TypeError: 'tuple' object is not callable

run()[0]
# <function __main__.run.<locals>.a()>

run()[0]()
# A

run()[1]()
# B

a, b = run()

a()
# A

b()
# B

x, y = run()

x()
# A

y()
# B

def run():
    a = 10
    b = 20

    class MyClass:
        def hello(self):
            pass

    def abc():
        pass

    def xyz():
        pass

    return MyClass


run()
# <class '__main__.run.<locals>.MyClass'>

4.3.7. Locals

def run(a=1):
    b = 1
    print(locals())


run()
# {'a': 1, 'b': 1}