DECORATORS:
===========
Decorator is a function that takes another function as an argument add some kinds of functionality without modifying the original functionality and returns a function.

Syntax:
	def decorator(func):
		add some functionality
		return func

1) how the function can take a function as an argument:
=======================================================
Syntax:
	def function-name(func):
		implementation

# Sending a function as an argument to another function:

def do_it_again(func):
    func()
    func()
    func()

def greets():
    print("Hi")
    print("Good Morning")
    print("Welcome to Ashok IT.")

do_it_again(greets)

2) how the function can return a function
==========================================
Syntax:
	def function-name(function(optional)):
		implementation
		return function

# Function returning a function:

def return_upper():
    return str.upper

to_upper = return_upper()   # function-aliasing
"""
renaming the function
or
define the another name to the function which we have defined is called as "function aliasing".
"""

result = to_upper("object oriented programming language")
print(result)

# print(to_upper("object oriented programming language"))

3) inner function
=================
writing a function inside the another function.
Syntax:
	def outer():
		def inner():	# local function to outer()
			implementation
		inner()
		inner()

# inner function

def parentFunction():
    print("This is the implementation of parentFunction()") # 1
    def childFunction1():
        print("This is the first child's implementation.")  # 3
    def childFunction2():
        print("This is the second child's implementation.") # 2

    # childFunction1()
    childFunction2()
    childFunction1()

parentFunction()
# childFunction1()
		
==============================================

Creating of a Decorator:
========================
Syntax:
	func = decorator(func)

# Creation of Decorator:

def decorator(function):
    def wrapperFunction():
        print("This is printed before the function is called.")
        function()
        print("This is printed after the function is called.")

    return wrapperFunction

def greetings():
    print("Hi")
    print("Good Morning.")
    print("Welcome to Ashok IT")

greetings = decorator(greetings)
greetings()

==================================================

Syntactic Decorator:
====================
@decorator:
def function(arg1, arg2, arg3,...):
	pass

# Syntactic Decorator

def decorator(function):
    def wrapperFunction():
        print("This is printed before the function is called.")
        function()
        print("This is printed after the function is called.")

    return wrapperFunction

@decorator
def greetings():
    print("Hi")
    print("Good Morning")
    print("Welcome To Ashok IT.")

greetings()