Eloquent Ruby

Chapter 27. Invent Internal DSLs

Rake. RSpec. ActiveRecord models. A build tool, a testing utility, and a database interface library. It seems unlikely that these three chunks of code could have anything in common, but they do. All three are examples of a particular style of programming, the internal Domain Specific Language, or DSL. More than any other technique, the internal DSL has come to represent the easy eloquence of Ruby; each is an illustration of how the language allows you to create tools that can solve whole classes of problems.

In this chapter we will look at building DSLs in Ruby. Actually, build is probably the wrong word: What we will really see is how you can grow a DSL, how you can start with an ordinary API and slowly transform ...