Most traditional programming languages provide several ways to abstract away complexities of code, and instead present a well defined interface.

What does that mean? Well, in simple terms it’s a restricted set of entry points into that code that make it clear how you can interact with it.

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Take, for example, a web page with a form that takes your username and password. The interface is made up of the username field, the password field, a ‘forgot my password’ link and perhaps a few other links. Other than that, you don’t really have any other access to what’s going on behind the scenes.

You can do the same over a piece of code - for example in many languages you would define a module or class that processes someone’s login information. You might expose a function for setting the username and password, something like:

login.request(username, password)

and perhaps a way to ask whether login was successful, and perhaps a ‘key’ to access the user’s information in other parts of the code once they have been confirmed.

Apart from these exposed functions, the rest of the encapsulated code is usually hidden away from the other parts of the program. Typically the developer’s tools will help out by listing the functions that are exposed as you write the program. Something like this:

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You can also define your own restricted interfaces around parts of spreadsheets as well - though it takes a little bit of knowledge of how a few features work together.

Later on we’re going to go through three examples based on the scenarios we talked about earlier:

1. Blocking out and even restricting navigation to data input areas.
2. Encapsulating a lookup table for reference data.
3. Encapsulating calculations, and using named ranges as the interface.

Until next time, thanks for reading!

– Brendan

p.s. Enjoy this message? Read more at the Hyland Quality Systems website.