Ruby样式访问模块和类的元素

module MyModule
  MY_CONSTANT = "Hello, world!"
end

puts MyModule::MY_CONSTANT # 输出 "Hello, world!"

class MyClass
  def initialize(name)
    @name = name
  end

  def say_hello
    puts "Hello, my name is #{@name}!"
  end
end

my_object = MyClass.new("John")
my_object.say_hello # 输出 "Hello, my name is John!"

class MyClass
  @@count = 0

  def initialize
    @@count += 1
  end

  def self.count
    @@count
  end
end

my_object1 = MyClass.new
my_object2 = MyClass.new
puts MyClass.count # 输出 2

class MyClass
  def self.say_hello
    puts "Hello, I'm a class method!"
  end
end

MyClass::say_hello # 输出 "Hello, I'm a class method!"

class MyClass
  def say_hello
    puts "Hello, I'm an instance method!"
  end
end

my_object = MyClass.new
my_object.say_hello # 输出 "Hello, I'm an instance method!"