Ruby:模块，要求并包含 [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:

#!/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.但这不起作用:(:

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:您需要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提供了将其混入的类的实例方法.

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

extend为将其混入的类提供类方法.

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

给出此阅读内容.

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