仅在将某些内容添加到列表时如何打印？

Question

I got an idea where you have a list etc. of [1,2,3,4,5] and my idea was that incase a number of those gets pop/deleted then it shouldn't print. Let's say etc. we remove number 3 . In that case our list would be [1,2,4,5] and the script should be usual. But whenever a value gets added to a list. Then print out the whole list so etc. add number 6 – > [1,2,4,5,6] - Print out the whole list.

The problem is that I don't want to get notified whenever there has been anything deleted so my idea from the beginning was to check the length of a list and then notify whenever it gets changed but then I realized that the wrong I am doing is that it going to notify whenever it gets added and/nor deleted which now why I am here.

What I did was a compare of a new_name_list vs old_name_list but this one is going to notify for whatever change that would be happens basically.

import names


def get_value(value):

     value = names.get_full_name()

     names_list = []
     for names in names.get_last_name():
        names_list.append(names)
        break

     identifier = ('{} {}').format(value, names_list)

     return identifier


if __name__ == '__main__':

    old_name_list = get_value()

    while True:
        new_name_list = get_value()
        if new_name_list not in old_name_list:
            print("Yay new name added")

        else:
            print('I will re try again in 5 sec')
            time.sleep(5)

My question is - How can I make it so it print only whenever the value of names_list will get notified ONLY when something gets added but not deleted?

etc.

1. [1,2,3,4,5] - print from beginning
2. [1,2,4,5] - Deleted 3 - Do not print
3. [1,2,4,5,6] - Print list, something got added
4. [1,4,5,6] - Deleted 2 - Do not print
5. .........

Answer 1

Algorithm could be the following:

1. Order old and new lists.
2. If length is equal -> compare element-to-element. If new list contains different elements than old list, means new values were added.
3. If new list length > old list length, also means, that new elements were added.

Example:

def detect_change(old_list, new_list):
    changed_flag = False
    old_list.sort()
    new_list.sort()
    if len(old_list) == len(new_list):
        for i in range(0, len(old_list)):
            if old_list[i] != new_list[i]:
                changed_flag = True
    elif len(old_list) < len(new_list):
        changed_flag = True
    return changed_flag

list1 = ["a", "b", "c", "d"]
list2 = ["a", "b", "c", "k"]

print(detect_change(list1, list2))