What is “Orthogonality”?

Question

What does \"orthogonality\" mean when talking about programming languages?

What are some examples of Orthogonality?

Answer 1

While talking about project decisions on programming languages, orthogonality may be seen as how easy is for you to predict other things about that language for what you've seen in the past.

For instance, in one language you can have:

str.split

for splitting a string and

len(str)

for getting the lenght.

On a language more orthogonal, you would always use str.x or x(str).

When you would clone an object or do anything else, you would know whether to use

clone(obj)

or

obj.clone

That's one of the main points on programming languages being orthogonal. That avoids you to consult the manual or ask someone.

The wikipedia article talks more about orthogonality on complex designs or low level languages. As someone suggested above on a comment, the Sebesta book talks cleanly about orthogonality.

If I would use only one sentence, I would say that a programming language is orthogonal when its unknown parts act as expected based on what you've seen. Or... no surprises.

;)