Abstraction

Abstraction is the concept of properly targeting our thinking around the level that makes most the contextual sense. It allows us to drill down and become more specific when we need to, or break out into broader more general concepts.

You use it everyday, in such an intuitive way that you may not even be aware of it. Let's say you're at the train station and you need to buy a train ticket.

You would simply ask:

Can I have a ticket for the AB train please?.

But you could equally say:

I need a piece of paper that holds ticketing information that I will be able to present to a ticket inspector which proves that I I am allowed to travel on the train from A to B and only on this train and on no other.

It's impractical and somewhat confusing to say the latter, but it's the latter that is implied and understood by the former.

Sometimes of course it pays to be more specific. If we're talking about the microbiology of the gut of a cow, it doesn't really matter that the cow's name is Sally, does it?

Abstraction in programming

In programming, abstraction allows us to break our software into different levels of logic appropriate for the context of the software. For example, using functions, we might be building a mail application.

At the top level we could have functions like sendMail, retrieveMail. This is perhaps the level our user might interact with our software. It's uncomplicated and clear.

At a lower level we might have some helper functions. For our sendMail function for example, we might have setUpConnection, encodeMessage, addHeaders, sendData etc. These all have could have further abstractions still. And so on so forth.

So what?

By breaking out our logic into these abstracted levels we make our code easier to develop and manage. It also makes it easier for us to avoid costly refactors or rewrites if we've made sensible abstractions that allow us to change or evolve the internals of a system without affecting the external interface.

Again, considering the mail application, if we wanted to change the type of server our application ran on we could do so without changing anything user-facing.

Abstraction is a powerful tool for designing software. It's also a powerful tool in our everyday lives.