ruby元编程实际使用实例

require 'rack/rpc'

class Server < Rack::RPC::Server
 def hello_world
  "Hello, world!"
 end

 rpc 'hello_world' => :hello_world
end

module RPC
  require 'rack/rpc'
  #require rpc/*.rb文件
  Dir.glob(File.join(File.dirname(__FILE__), 'rpc', "*.rb")) do |file|
   require file
  end
  class Runner < Rack::RPC::Server
   #include rpc/*.rb and regsiter rpc call
   #eg. rpc/god.rb  god.hello
   @@rpc_list = []
   Dir.glob(File.join(File.dirname(__FILE__), 'rpc', "*.rb")) do |file|
    rpc_class = File.basename(file).split('.rb')[0].capitalize
    rpc_list = []
    
    #加载module下的方法到Runner这个类下面
    eval "include Frigga::RPC::#{rpc_class}"
    #获取声明的RPC接口
    eval "rpc_list = Frigga::RPC::#{rpc_class}::RPC_LIST"
    rpc_list.each do |rpc_name|
     #alias一个新的rpc方法，叫old_xxxx_xxxx
     eval "alias :old_#{rpc_class.downcase}_#{rpc_name} :#{rpc_name}"

     #重新定义rpc方法，添加一行日志打印功能，然后再调用old_xxxx_xxxx rpc方法
     define_method "#{rpc_class.downcase}_#{rpc_name}".to_sym do |*arg|
      Logger.info "[#{request.ip}] called #{rpc_class.downcase}.#{rpc_name} #{arg.join(', ')}"
      eval "old_#{rpc_class.downcase}_#{rpc_name} *arg"
     end 

     #注册RPC调用
     rpc "#{rpc_class.downcase}.#{rpc_name}" => "#{rpc_class.downcase}_#{rpc_name}".to_sym

     #添加到全局变量，汇总所有的rpc方法
     @@rpc_list << "#{rpc_class.downcase}.#{rpc_name}"
    end
   end
   
   def help
    rpc_methods = (['help'] + @@rpc_list.sort).join("\n")
   end
   rpc "help" => :help

  end
 end #RPC

module RPC
  module Ip
   #RPC_LIST used for regsiter rpc_call
   RPC_LIST = %w(list add del)

   def list
    $white_lists
   end   

   def add(ip) 
    if ip =~ /^((25[0-5]|2[0-4]\d|[0-1]"succ"
    else
     return "fail"
    end
   end

   def del(ip)
    if $white_lists.include"succ"
    else
     return "fail"
    end    
   end

   def write_to_file
     File.open(IP_yml, "w") do |f|
      $white_lists.uniq.each {|i| f << "- #{i}\n"}
     end
   end
  end 
 end

  class ChefDSL
   def template(path, &block)
    TemplateDSL.new(path, &block)
   end
  end

  class TemplateDSL
   def initialize(path, &block)
    @path = path
    instance_eval &block
   end

   def source(source); @source = source; end
   def owner(owner);  @owner = owner; end
   def mode(mode);   @mode  = mode;  end
  end

 require 'colorize'
 class Tip
  def self.ask(stat = true, &block)
   new(&block).ret if stat == true
  end

  attr_reader :ret
  def initialize(&block)
   @opt = []
   @caller = {}
   @banner = ""
   @ret = false
   self.instance_eval(&block)
   print "#{@banner} [#{@opt.join('/')}]: ".light_yellow
   loop do
    x = gets.chomp.strip.to_sym
    if @opt.include"\n#{@banner} [#{@opt.join('/')}]: ".light_yellow
      next
     else
      return @ret
     end
    else
     print "input error, please enter [#{@opt.join('/')}]: ".light_yellow
    end
   end

  end

  def on(opt, &block)
   @opt << opt
   @caller[opt] = block if block_given?
  end
  def banner(str)
   @banner = str
  end
 end