Ruby:模块、需要和包含 [英] Ruby: module, require and include

问题描述

我正在尝试使用 Ruby 模块(mixins).

I'm trying to use Ruby modules (mixins).

我有 test.rb:

I have test.rb:

#!/usr/bin/env ruby
require_relative 'lib/mymodule'

class MyApp
  include MyModule
  self.hallo
end

和 lib/mymodule.rb:

and lib/mymodule.rb:

module MyModule
  def hallo
    puts "hallo"
  end
end

非常简单的设置.但它不起作用:(:

Quite simple setup. But it does not work :( :

ruby test.rb
test.rb:8:in `<class:MyApp>': undefined method `hallo' for MyApp:Class (NoMethodError)
        from test.rb:6:in `<main>'

我的错误在哪里?

推荐答案

简而言之:你需要extend而不是include模块.

In short: you need to extend instead of include the module.

class MyApp
  extend MyModule
  self.hallo
end

include 为混合它的类提供实例方法.

include provides instance methods for the class that mixes it in.

extend 为混合它的类提供类方法.

extend provides class methods for the class that mixes it in.

阅读这个.

这篇关于Ruby:模块、需要和包含的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！