20.closures_decorators.py

# Example 1 : A simple closure function.
print('>>>> Example - 1 >>>>')


def make_multiplier_of(n):
    def multiplier(x):
        return x * n

    return multiplier


times_3 = make_multiplier_of(3)
times_5 = make_multiplier_of(5)

print(times_3(9))
print(times_5(3))
print(times_5(times_3(2)))


# Example 2 : A simple decorators function.
print('\n')
print('>>>> Example - 2 >>>>')


def make_pretty(func):
    def inner_fun():
        print("I got decorated")
        func()

    return inner_fun


def ordinary():
    print("I am ordinary")


# call ordinary() function.
ordinary()

# let's decorate this ordinary function.
pretty = make_pretty(ordinary)
pretty()


# Example 3 : @ symbol along with the name of the decorator function.
print('\n')
print('>>>> Example - 3 >>>>')


@make_pretty
def ordinary():
    print("I am ordinary function as decorator function")


# call ordinary() function as decorator function.
ordinary()


# Example 4 : @ symbol along with the name of the decorator function with parameters.
print('\n')
print('>>>> Example - 4 >>>>')


def smart_divide(func):
    def divide_fun(a, b):
        print("I am going to divide", a, "and", b)
        if b == 0:
            print("Whoops! cannot divide")
            return

        return func(a, b)

    return divide_fun


@smart_divide
def divide(a, b):
    print(a / b)


divide(4, 2)