Decorator in Python

A decorator is a design pattern in Python that allows a user to add new functionality to an existing object without modifying ...

A decorator is a design pattern in Python that allows a user to add new functionality to an existing object without modifying its structure.
Decorators are usually called before the definition of a function you want to decorate.
This is also called metaprogramming as a part of the program tries to modify another part of the program at compile time.
two different kinds of decorators in Python:

Function decorators
Class decorators

def input_decorator(func):
    def input_number():
        nth_number = int(input("How many number do you want to enter.\n"))
        legal_number = []
        illegal_number = []
        for i in range(nth_number):
            number = input("Enter number : ")
            if float(number)<=0 or '.' in number:
                illegal_number.append(number)
            else:
                legal_number.append(int(number))
        list_of_legal_and_illegal_number = [legal_number,illegal_number]
        return func(list_of_legal_and_illegal_number)
    return input_number


def grouping_decorator(func):
    def numbers_test(args):
        odd = []
        even = []
        prime = []
        composite = []
        for i in args[0]:
            if i%2!=0:
                odd.append(i)
            else:
                even.append(i)
        
        for i in odd:
            if i == 1:
                continue
            elif i==3 or i==5 or i==7:
                prime.append(i)
            else:
                if i%3!=0 and i%5!=0 and i%7!=0:
                    prime.append(i)
                else:
                    composite.append(i)
        for i in even:
            if i==2:
                prime.append(i)
            else:
                composite.append(i)
        composite.sort()
        prime.sort()        
        list_of=[odd,even, prime, composite]
        invalid_number = args[1]
        return func(list_of,invalid_number)


    return numbers_test


@input_decorator
@grouping_decorator
def mean_calculator(args,args1):
    a=','.join(args1)
    print("Invalid numbers : ", a) 
    if not args[0]:
        print('no odd')
    else:
        print("Mean of odd numbers : ",sum(args[0])/len(args[0]))
    if not args[1]:
        print('no even')
    else:
        print("Mean of even numbers : ",sum(args[1])/len(args[1]))
    if not args[2]:
        print('no prime')
    else:
        print("Mean of prime numbers : ",sum(args[2])/len(args[2]))
    if not args[3]:
        print('no composite')
    else:
        print("Mean of composite numbers : ",sum(args[3])/len(args[3]))

mean_calculator()