Metaprogramming Ruby 2

Quiz: A Better DSL

Where you’re left alone to develop a new version of the RedFlag DSL.

Your boss wants you to add a setup instruction to the RedFlag DSL:

blocks/redflag_3/events.rb

setup do
  puts "Setting up sky"
  @sky_height = 100
end

setup do
  puts "Setting up mountains"
  @mountains_height = 200
end

event "the sky is falling" do
  @sky_height < 300
end

event "it's getting closer" do
  @sky_height < @mountains_height
end

event "whoops... too late" do
  @sky_height < 0
end

In this new version of the DSL, you’re free to mix events and setup blocks (setups for short). The DSL still checks events, and it also executes all the setups before each event. If you run redflag.rb on the previous ...