Goal DSL for XFA manipulation

dsl.rb

data = {:name => 'Bob', :gender => 'm', :relation => 'Uncle' }

pdfs = capture_pdfs do
  pdf :basic_info do
    text 'name', data[:name]
    radio_group 'sex' do
      fill 'male',   :when => data[:gender] == 'm'
      fill 'female', :when => data[:gender] == 'f'
    end
    checkbox_group 'relation' do
      check 'parent',  :when => ['Mom', 'Dad'].include?(data[:relation])
      check 'sibling', :when => ['Brother', 'Sister'].include?(data[:relation])
      check 'other',   :unless => ['Brother', 'Sister', 'Mom', 'Dad'].include?(data[:relation])
      # OR
      case data[:relation]
      when 'Mom', 'Dad'
        check 'parent'
      when 'Brother', 'Sister'
        check 'sibling'
      else
        check 'other'
      end
    end
  end
end

pdf.rb

class PDF
  def initialize(name=nil, opts={})
    @name = name if name
    @fields = []
  end

  def text(name, value)
    @fields << {:name => name, :value => value, :type => :text}
  end

  def radio_group(name, &blk)
    fields = []
    # TODO: replace w/ singleton method?
    PDF.instance_eval do
      send(:define_method, :fill) do |value, opts={}|
        return if opts.has_key?(:when)   && !opts[:when]
        return if opts.has_key?(:if)     && !opts[:if]
        return if opts.has_key?(:unless) && opts[:unless]
        fields << {:name => name, :value => value, :type => :radio}
      end
      blk.call
      send(:undef_method, :fill)
    end

    @fields += fields
  end

  def checkbox_group(name, &blk)
    fields = []
    # TODO: replace w/ singleton method?
    PDF.instance_eval do
      send(:define_method, :check) do |value, opts={}|
        return if opts.has_key?(:when)   && !opts[:when]
        return if opts.has_key?(:if)     && !opts[:if]
        return if opts.has_key?(:unless) && opts[:unless]
        fields << {:name => name, :value => value, :type => :checkbox}
      end
      blk.call
      send(:undef_method, :check)
    end

    @fields += fields
  end
end

module Kernel
  def pdf(name=nil, opts={}, &blk)
    r = PDF.new(name, opts)
    r.instance_eval(&blk)
    r
  end
end