Ruby元编程基础学习笔记整理
笔记一: # test.rb class Greeting def initialize(text) @text = text end def welcome @text end end my_obj = Greeting.new("hello") puts my_obj.class puts my_obj.class.instance_methods(false) #false means not inherited puts my_obj.instance_variables result => Greeting welcome @text 总结: 应用示例: mongo API for ruby => Mongo::MongoClient # testmongo.rb require 'mongo' require 'pp' include Mongo # the members of replcation-set # test mongodb server version 2.6.0 host = "192.168.11.51" # The port of members # If the port is 27017 by default then otherport don't need to assignment otherport = "" port = otherport.length != 0 ? otherport : MongoClient::DEFAULT_PORT opts = {:pool_size => 5,:pool_timeout => 10} # Create a new connection client = MongoClient.new(host,port,opts) # puts client.class puts client.class.constants puts client.instance_variables puts client.class.instance_methods(false) 分别输出 Constant,Instance Attribute,Instance Method 笔记二:动态调用 class MyClass def my_method(args) args * 10 end end obj = MyClass.new puts obj.my_method(5) puts "**" puts obj.send(:my_method,6) 结果: 50 ** 60 可以使用object#send()取代点标记符来调用MyClass#my_method()方法: obj.send(:my_method,6) send()方法第一个参数是要发送给对象的消息,可以是符号(:symbol)或字符串,其他参数会直接传递给调用的方法。 笔记三:符号和字符串的区别 puts 1.send(:+,4) => 5 String#to_sym(),String#intern() => string to symbol String#to_s(),String#id2name() => symbol to string "caoqing".to_sym() => :caoqing :caoqing.to_s() => "caoqing" 动态派发中使用模式派发(pattern dispatch)的方法。 puts obj.class.instance_methods(true).delete_if{ |method_name| method_name !~ /^my/} result => my_method 笔记四:动态定义 class MyClass define_method :my_method do |args| args * 3 end end obj = MyClass.new puts obj.my_method(10) 结果: 单件方法允许给单个对象增加一个方法。singleton methods # test.rb str = "My name is caoqing." def str.title? self.upcase == self end puts str.title? puts str.methods.grep(/^title?/) puts str.singleton_methods 结果: false title? title? 笔记五: obj.my_method Cla.class_method Duck Typing:对象能不能响应方法,可以是普通方法或者单件方法。 def obj.method # method body end obj可以是对象引用,常量类名或self。 类宏(Class Macro) Eigenclass class << obj code end 如果想获取eigenclass的引用,则可以在离开该作用域时返回self: 附录: # test.rb class Foo @@var = "lion" def self.method01 puts "cat" @name = "cat" @@var = "cat" puts @name end def self.method02 puts "tiger" @name = "tiger" @@var = "tiger" puts @name end def self.method03 puts "dog" @name = "dog" @@var = "dog" puts @name end def putsname puts @name puts @@var end end obj = Foo.new # obj.method01 => (NoMethodError) obj.putsname => lion Foo.method01 Foo.method02 Foo.method03 obj.putsname 结果: lion cat cat tiger tiger dog dog dog (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |