ChainMethod extension for Object

chainmethods.rb

class ChainMethod
  def initialize(method_name, params = [], callbacks = {})
    @method_name = method_name
    @params = params
    @callbacks = callbacks
  end

  def call(base_object)
    # preparation work
    result = base_object
    block = @params.pop if @params.last.is_a?(Proc)

    # calling before_callback if passed
    @callbacks[:before_callback].call(@params, result) if @callbacks[:before_callback].is_a?(Proc)

    # main stuff
    if @params.nil?
      result = result.send(@method_name.to_sym)
    elsif block.is_a?(Proc)
      result = result.send(@method_name, *@params, &block)
    else
      result = result.send(@method_name, *@params)
    end

    # calling after_callback
    @callbacks[:after_callback].call(@params, result) if @callbacks[:after_callback].is_a?(Proc)

    # returning value
    result
  end
end

class Object
  def chain_methods(chain)
    chain.inject(self) { |result, chain_method| chain_method.call(result) }
  end
end

callback_proc = Proc.new do |params, result|
  puts "params = #{params.inspect}"
  puts "result = #{result.inspect}"
end

puts ["a", "b", "c"].chain_methods([
  ChainMethod.new("reverse"),
  ChainMethod.new("uniq"),
  ChainMethod.new("map", [proc{|x| x.upcase}], {:after_callback => callback_proc}),
  ChainMethod.new("map", [proc{|x| x.downcase}], {:before_callback => proc{ |params| puts params.inspect}, :after_callback => callback_proc})
  ]).inspect