External DSL

[amattsmith]

Create external DSL. Original DSL’s are internal and written in Ruby. To be able to store rules externally an external DSL is needed. This would allow for a lot of new functionality to be created, i.e. a BRMS.

original LH ticket

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[robblovell]

One step toward putting rules in files is to be able to define rules via strings. One idea is to take the ruby code for the rules, in the format it is used to define rules, and to pass this to a "s_rules" or "rules_from_string" that evals it. This would be a function for the Rulebook in rulebook.rb:

    def s_rules(astring)
      eval astring
    end

This is used like so:

$LOAD_PATH << File.join(File.dirname(__FILE__), '../lib/')
require 'ruleby'

include Ruleby

class Q
  def initialize(status,message)
    @status = status
    @message = message
  end
  attr :status, true
  attr :message, true
end

engine :engine do |e|
  r=Rulebook.new(e)
  # here is the string with the rules in it.
  a_string = "
  def rules
    rule [Q, :p, m.status == :HELLO]  do |v|
      puts v[:p].message
    end
  end
  rules
  "
  r.s_rules(a_string);
  e.assert Q.new(:HELLO, 'Hello')
  e.match
end