From whom abstraction hides implementation?

Question

I know the architecture, how we can implement abstraction using the interface and an abstract class. But from whom we are hiding the implementation?

As a developer, anyone can click on that method and can see the classes which are giving implementations for those abstract methods.

As a user, he will be only facing UI, so he is not going to see the code anyway.

Then my question from whom we are hiding the implementation?

We aren't hiding it in a security sense, but to stop people writing code which depends on implementation details: https://stackoverflow.com/questions/383947/what-does-it-mean-to-program-to-an-interface?r=SearchResults&s=1|204.3958 — tgdavies, Aug 22 '20 at 06:01
Sometimes as a developer, you will be working on a big project. There will be other developers involved as well, "hiding implementation" also make it harder for others to change the data by mistake. — Stephan, Aug 22 '20 at 06:04
@tgdavies Depending on the specifics, it can in fact be a security matter, even in Java. — chrylis -cautiouslyoptimistic-, Aug 22 '20 at 06:19
Dividing the world into **developers** and **users** is misleading; all developers _are_ users of other developers' work. In a complex application, I'm often the developer of a piece that I then turn around and consume from another layer, several times in sequence. — chrylis -cautiouslyoptimistic-, Aug 22 '20 at 06:20

score 2 · Answer 1 · answered Aug 22 '20 at 06:05

We are hiding it from clients of the interface, so that they don't depend on things which might change. A client of an interface is a piece of code which calls the interface.

Let's say I write a stack interface:

interface Stack {
  push(String s);
  String pop();
}

and an implementation:

class StackImpl {
  public List contents;
  public void push(String s) {
     ...
  }
  ...
}

If clients use StackImpl, they might start accessing the contents directly, which will mean that I can't change the implementation to use an array without breaking all the clients. If they only use Stack, we can improve the implementation without affecting the clients.

From whom abstraction hides implementation?

1 Answers1