Ruby7 OOP

摘要

自己实现 attr_accessor

Everything is Object 一切皆对象

a = "hello" a.class # => String  b = 3.14 b.class # => Float  c = %w[pear cat horse] c.class # => Array

Instance Method & Instance Attribute 实例方法，实例属性

1. Instance Method: 实例方法，成员方法，成员函数
2. Instance Attribute: 实例变量，成员属性，属性(property)，使用@定义

# class  class User    def initialize name, age     @name = name     @age = age   end    # getter   def name     @name   end    def age     @age   end  end  user = User.new('Hello', 18) puts user.name puts user.age

# class  class User    def initialize name, age     @name = name     @age = age   end    # getter   def name     @name   end    def age     @age   end    # setter   def name= name     @name = name   end    def age= age     @age = age   end   end   user = User.new('Hello', 18) puts user.name puts user.age  puts '-' * 30 user.name = 'hello 2' user.age = 20 puts user.name puts user.age 

# class, attr_reader, attr_writer  class User    attr_reader :name   attr_reader :age    attr_writer :name   attr_writer :age    def initialize name, age     @name = name     @age = age   end  end  user = User.new('Hello', 18) puts user.name puts user.age  puts '-' * 30 user.name = 'hello 2' user.age = 20 puts user.name puts user.age 

# class, method  class User    attr_accessor :name   attr_accessor :age    def initialize name, age     @name = name     @age = age   end    def say_hi     puts "hello  #{@name}, i am #{@age}"   end end  user = User.new('Hello', 18) user.say_hi

Class Method & Class Variable 类方法，类变量

1. Class Method:类方法，静态方法
2. Class Variable:类变量, 使用@@定义

# class, method  class User    attr_accessor :name   attr_accessor :age    @@counter = 0    def initialize name, age     @name = name     @age = age     @@counter += 1   end    def say_hi     puts "hello  #{@name}, i am #{@age}"   end    def self.get_counter     @@counter   end  end  puts User.get_counter user = User.new('Hello', 18) user.say_hi puts User.get_counter

Access Control 访问控制

1. public
2. protected
3. private

# class, method  class User    attr_accessor :name   attr_accessor :age    def initialize name, age     @name = name     @age = age   end     def say_hello     puts "hello..."     say_hi     say_hey   end    def say_hi     puts "hello  #{@name}, i am #{@age}"   end    def say_hey     puts "hey, i am #{@name}"   end    protected :say_hi, :say_hey end  user = User.new('Hello', 18) user.say_hello

Dynamic Ruby 动态特性

User内幕

# attr_accessor 方法从哪里来的？ class User   # ... end  User.class # => class  # Class.attr_accessor 背后的秘密  # define_method  # attr_accessor, define_method  define_method :hello do   puts "hello world" end  hello

自己实现 attr_accessor

# define_method  class User   # attr_accessor :name   # attr_accessor :age    def self.setup_accessor var     define_method var do       instance_variable_get "@#{var}"     end      define_method "#{var}=" do |value|       instance_variable_set "@#{var}", value     end   end      setup_accessor :name   setup_accessor :age    def initialize name,age     @name = name     @age = age   end end   user = User.new "hello", 18 puts user.name  puts '-' * 30 user.name = "hello 2" puts user.name