Question

I’m currently working my way through Code Complete and the word “interface” keeps popping up! I’m trying to get my head round what an interface is. Can you define the term? Also what actually makes up a “class interface”?

Answer 1

I think a good way to define an interface is as follows

An interface is a contract specifying a set of methods, fields and properties which will be available on any implementing object

The actual implementation from language to language may have funny little differences but the principle holds.

I considered adding implemented interfaces to the list above but left it off because it seemed to be a bit too language specific. I think it’s OK though because the end effect is almost the same. Tacking on more interfaces is just adding more methods, fields and properties to the contract.