DECORATORS:
===========

Docstring:
=========

# Docstring

# used to define the description about any block (class, function, method etc.)
# during the debugging.
# can be defined with """ """

def fun1(t):
    """
    This function is defined to print greetings
    like: "good morning"
    "good afternoon"
    "good evening"
    and "good night".
    """

    if t >= 0 and t < 12:
        print("Good Morning.")

    elif t >= 12 and t < 16:
        print("Good Afternoon.")

    elif t >= 16 and t < 20:
        print("Good Evening.")

    else:
        print("Good Night.")


fun1(6)

print(help(fun1))
print(help(print))

Preserving the Original Name and Docstring of the 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 greets():
    """
    This function says hello when we called.
    """
    print("Hello All.")

print(greets.__name__)
help(greets)

==> To preserve the identity of function and the documentation string of the function, we can use "decorator".

wraps() ==> 
functools

import functools

def decorator(function):
    @functools.wraps(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 greets():
    """
    This function says hello when we called.
    """
    print("Hello All.")

print(greets.__name__)
help(greets)

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

Reusing Decorator:
==================
1) create a python file for defining decorator
ex: decorators.py
==================

import functools

def iterativeFunction(function):
    @functools.wraps(function)
    def wrapperFunction():
        print("This is printed before the function is called.")
        function()
        print("This is printed after the function is called.")

    return wrapperFunction

2) Import that decorator into application/anoter python file where we want to reuse it.
Syntax:
	from decorator-module-name import decoartor-name

from decorators import iterativeFunction

@iterativeFunction
def greets():
    print("Hello All.")

@iterativeFunction
def welcome():
    print("Welcome To Ashok IT.")

greets()
welcome()

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

Decorators With Parameters:
===========================

wrapper(with parameters)
Syntax:
	def wrapper(*args, **kwargs)

# Decorator with parameters

import functools

from Decortaors.Day_02.decorators import iterativeFunction


def iterateFunction(function):
    @functools.wraps(function)
    def wrapper(*args, **kwargs):
        function(*args, **kwargs)
        function(*args, **kwargs)

    return wrapper

@iterateFunction
def greets(name):
    print("Hello",name)

# greets("Rakesh")

pname = "Suresh"
greets(name = pname)

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

Returning values from Decorator Function:
=========================================

import functools

def decorator(function):
    @functools.wraps(function)
    def innerFunction(*args, **kwargs):
        return function(*args,**kwargs)

    return innerFunction

@decorator
def addition(n1,n2,n3):
    print("The sum of {n1}, {n2} and {n3} is = ")
    return n1 + n2 + n3

print("The sum is = ",addition(11,111,1111))

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

Do we define the Decorators with Arguments?:
============================================
Yes
It's all based on the inner function of the decorator.

If the inner function of the decorator with parameters ==> we can send arguments to decorator.

otherwise ==> we can't

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

Chaining Decorators:
====================
Defining multiple decorators to a single function is called as "Chaining Decorator".

# Chaining Decorator

import functools
def splitString(function):
    @functools.wraps(function)
    def innerFunction(*args,**kwargs):
        return function(*args, **kwargs).split()

    return innerFunction

def toUpper(func):
    @functools.wraps(func)
    def wrapperFunction(*args, **kwargs):
        return func(*args,**kwargs).upper()

    return wrapperFunction

@splitString
@toUpper
def String(data):
    return data

print(String("object oriented programming language"))