来自编程Ruby 1.9

We’ll make a couple of points about the include statement before we go on. First, it has nothing to do with files. C programmers use a preprocessor directive called #include to insert the contents of one file into another during compilation. The Ruby include statement simply makes a reference to a module. If that module is in a separate file, you must use require (or its less commonly used cousin, load) to drag that file in before using include. Second, a Ruby include does not simply copy the module’s instance methods into the class. Instead, it makes a reference from the class to the included module. If multiple classes include that module, they’ll all point to the same thing. If you change the definition of a method within a module, even while your program is running, all classes that include that module will exhibit the new behavior.

来自编程Ruby 1.9

We’ll make a couple of points about the include statement before we go on. First, it has nothing to do with files. C programmers use a preprocessor directive called #include to insert the contents of one file into another during compilation. The Ruby include statement simply makes a reference to a module. If that module is in a separate file, you must use require (or its less commonly used cousin, load) to drag that file in before using include. Second, a Ruby include does not simply copy the module’s instance methods into the class. Instead, it makes a reference from the class to the included module. If multiple classes include that module, they’ll all point to the same thing. If you change the definition of a method within a module, even while your program is running, all classes that include that module will exhibit the new behavior.

下面是require和include之间的一些基本区别:

要求:

Require从文件系统读取文件，解析它，保存到内存中，并在给定的位置运行它，这意味着如果你在脚本运行时更改了任何内容，那么这些更改将不会反映出来。 我们按名称要求文件，而不是按模块名。 它通常用于库和扩展。

包括:

当你将一个模块包含到你的类中时，它的行为就像你将模块中定义的代码插入到你的类中一样。 我们包含模块名，而不是文件名。 它通常用于干涸代码和删除代码中的重复。

例如:当你使用require 'math'时，你必须写math::PI。 但是当你使用include math时，你可以简单地写成PI。

您曾经尝试过要求一个模块吗?结果如何?试试:

MyModule = Module.new
require MyModule # see what happens

模块不是必需的，只是包含的!

包括 如下所示，当你将一个模块包含到你的类中时，就好像你将模块中定义的代码插入到类中，在那里你“包含”了它。它允许' mixin '行为。它用于DRY代码以避免重复，例如，如果模块中有多个类需要相同的代码。

负载 load方法几乎类似于require方法，除了它不跟踪库是否已加载。因此，可以多次加载一个库，而且在使用load方法时，必须指定“。Rb:库文件名的扩展名。

需要 require方法允许您加载一个库，并防止它被多次加载。如果你尝试在第一次之后加载相同的库，require方法将返回' false '。require方法只需要在你正在加载的库定义在一个单独的文件中，这是通常的情况。

你可以选择这个 http://ionrails.com/2009/09/19/ruby_require-vs-load-vs-include-vs-extend/