利用 Ruby 进行 UDP 通信

收信端

require 'socket'
u1 = UDPSocket.open()
u1.bind("0.0.0.0", 10000)
p u1.recvfrom(65536)

发信端

require 'socket'
u2 = UDPSocket.new()
u2.connect('localhost', 10000)
u2.send('Hello world!' , 0)

接收结果
["Hello world!", ["AF_INET", 32818, "localhost", "127.0.0.1"]]

原文: http://d.hatena.ne.jp/emergent/20071225/1198510691

Rails ActionMailer send mail using GMail

在config/environment.rb文件末添加ActionMailer配置，在插件目录里加入Net::SMTP补丁。

require 'smtp_tls'
ActionMailer::Base.delivery_method = :smtp
ActionMailer::Base.server_settings = {
  :address => "smtp.gmail.com", 
  :port => 587, 
  :domain => "localhost", 
  :authentication => :plain, 
  :user_name => "test.yu@gmail.com", 
  :password => "********"  
}

vendor/plugins/action_mailer_tls/init.rb

require_dependency 'smtp_tls'

vendor/plugins/action_mailer_tls/lib/smtp_tls.rb

require "openssl"
require "net/smtp"
Net::SMTP.class_eval do
  private
  def do_start(helodomain, user, secret, authtype)
    raise IOError, 'SMTP session already started' if @started
    check_auth_args user, secret, authtype if user or secret

    sock = timeout(@open_timeout) { TCPSocket.open(@address, @port) }
    @socket = Net::InternetMessageIO.new(sock)
    @socket.read_timeout = 60 #@read_timeout

    check_response(critical { recv_response() })
    do_helo(helodomain)

    raise 'openssl library not installed' unless defined?(OpenSSL)
    starttls
    ssl = OpenSSL::SSL::SSLSocket.new(sock)
    ssl.sync_close = true
    ssl.connect
    @socket = Net::InternetMessageIO.new(ssl)
    @socket.read_timeout = 60 #@read_timeout
    do_helo(helodomain)

    authenticate user, secret, authtype if user
    @started = true
  ensure
    unless @started
      # authentication failed, cancel connection.
      @socket.close if not @started and @socket and not @socket.closed?
      @socket = nil
    end
  end

  def do_helo(helodomain)
    begin
      if @esmtp
        ehlo helodomain
      else
        helo helodomain
      end
    rescue Net::ProtocolError
      if @esmtp
        @esmtp = false
        @error_occured = false
        retry
      end
      raise
    end
  end

  def starttls
    getok('STARTTLS')
  end

  def quit
    begin
      getok('QUIT')
    rescue EOFError
    end
  end
end

reference:http://blog.pomozov.info/posts/how-to-send-actionmailer-mails-to-gmailcom.html

difference usage obj.send and mod.module_eval

class A
 def fred
   puts "In Fred"
 end
  
 def create_method(name, &block)
   self.class.send(:define_method, name, &block)  # obj.send 
 end
  
  def custom_method(name, &block)
    self.class.module_eval {define_method(name, &block)} # mod.module_eval, class_eval alias module_eval
    # A.module_eval {define_method(name, &block)}
  end
  
 define_method(:wilma) { puts "Charge it!" }

end

class B < A
  define_method(:barney, instance_method(:fred)) #
end

b = B.new
p b

b.barney

b.wilma

b.create_method(:betty) { puts 'betty' }
b.betty

b.custom_method(:test) {puts 'test'}
b.test

##
#In Fred
#Charge it!
#betty
#test