Singleton 类的继承

Created: November-22, 2018

子类化也是子类 Singleton 类

class Example
end

Example.singleton_class #=> #<Class:Example>

def Example.foo
  :example
end

class SubExample < Example
end

SubExample.foo #=> :example

SubExample.singleton_class.superclass #=> #<Class:Example>

扩展或包含模块不会扩展 Singleton 类

module ExampleModule
end

def ExampleModule.foo
  :foo
end

class Example
  extend ExampleModule
  include ExampleModule
end

Example.foo #=> NoMethodError: undefined method