Question

Open-Closed Principle: (answer all the questions) a. Give the one sentence summary b Describe what it means c Why is it a good idea? d. What pattern uses it to add functionality, and how?

Answer 1

1.The summary is software items (classes, functions, modules) should be open for extension, but closed for modification.

2. This means that such an item will alow extension of its behaviour without modifying its
source code.

3.It is a good idea because if we our class is in a library or used somewhere and then if we
are changing the code for modification, then other programs depending on it also gets changed
and this is an issue but if we extend its behaviour by implementing inheritance , then in that
case whatever programs depeding on the original class won't have any issues and we can
use the base class with extended properties as per our requirement.

4.As per part 3, we can add functionality by using inheritance without changing the original source code and can add extended functionality.