Contents

module GamesDice
  # convert integer die result into value used in a game (e.g. 1 for a 'success')
  class MapRule

    # trigger_op, trigger_value, mapped_value and mapped_name set the attributes of the same name
    #  rule = RPGMapRule.new( 6, :<=, 1, 'Success' ) # score 1 for a result of 6 or more
    def initialize trigger_value, trigger_op, mapped_value=0, mapped_name=''

      if ! trigger_value.respond_to?( trigger_op )
        raise ArgumentError, "trigger_value #{trigger_value.inspect} cannot respond to trigger_op #{trigger_value.inspect}"
      end

      @trigger_value = trigger_value
      @trigger_op = trigger_op
      raise TypeError if ! mapped_value.is_a? Numeric
      @mapped_value = Integer(mapped_value)
      @mapped_name = mapped_name.to_s
    end

    # an Integer value or Range that will be mapped to a single value. #trigger_op is called against it
    attr_reader :trigger_value

    # a valid symbol for a method, which will be called against #trigger_value with the current
    # die result as a param. If the operator returns true for a specific die result, then the
    # mapped_value will be used in its stead. If the operator returns nil or false, the map is not
    # triggered. All other values will be returned as the result of the map (allowing you to
    # specify any method that takes an integer as input and returns something else as the end result)
    attr_reader :trigger_op

    # an integer value
    attr_reader :mapped_value

    # a string description of the mapping, e.g. 'S' for a success
    attr_reader :mapped_name

    # runs the rule against test_value, returning either a new value, or nil if the rule does not apply
    def map_from test_value
      op_result = @trigger_value.send( @trigger_op, test_value )
      return nil unless op_result
      if op_result == true
        return @mapped_value
      end
      return op_result
    end
  end # class MapRule
end # module GamesDice

Version data entries

1 entries across 1 versions & 1 rubygems

Version	Path
games_dice-0.0.3	lib/games_dice/map_rule.rb