From: dc <dc.pikkle@...>
Date: 2008-12-07T23:58:46+09:00
Subject: creating a DSL: adding random methods

hi -

I'm trying to create a simple DSL, using method missing.

i want to be able to add different event logic for different
instances, defined in their own files.
trivial example:

# eg in fred.rb
event :say do
  "hi this is fred!"
end

# and joe.rb
event :say do
  "joe doesnt say much"
end


so i have a class to implement/create the DSL methods:

  def event evt, &block
    puts "event: #{evt} , #{event}"
    str = "
      def #{evt}
        #{block}
      end
    "
    puts str
    self.class.class_eval(str)
  end


after loading the individual fred.rb file in
class Brain
  def self.load(filename)
    dsl = new
    dsl.instance_eval(File.read(filename))
  end

then when the event XX do is encountered, i am getting:

ArgumentError: ./parser.rb:37:in ‘event’: wrong number of arguments (0
for 1)

# this is the method call
event :say do
   puts ".code here.."
end

# calling this
def event evt, &block


i was expecting "say" to be passed as the evt (method name) and block
to be the code block after do.
perhaps i need to yield something back to the caller?

appreciate any tips on this!

/dc