如何在不编辑宝石来源的情况下将方法添加到红宝石宝石? [英] How do I add a method to a ruby gem without editing the gem source?

问题描述

我正在使用acts_as_taggable_on gem，并且想向其中一个gem源文件(tag.rb)添加方法，但是我不想以任何方式更改gem源.

我尝试在/app/models目录或/lib目录中创建自己的tag.rb文件，然后向该文件添加所需的方法，希望ruby合并两个tag.rb文件

但是我得到一个NoMethodError: undefined method ...

我想念什么?

解决方案

我认为重新打开Tag类是正确的做法.除非它对您的代码真正有意义，否则我不会介绍其他级别的继承.

我不确定，为什么要重新打开Tag类不起作用.一些想法:

1-当您编写自己的Tag类时，它是否来自ActiveRecord :: Base? Tag类中的Tag类的作用与之类似，我可以看到忽略它可能使事情变得混乱.

2-如果我需要放置重新打开单个方法的插件类的代码的地方，则可能会将其放在初始化文件中(例如config/initializers/tag_patch.rb).只是为了保持清洁.

3-如果其他所有方法均失败，并且您仍然无法正确打开Tag类(无论出于何种原因)，则可以尝试使用其他元编程技术来添加该方法.例如:

Tag.send(:define_method, method_name) do 
  #code for your method
end

I am using the acts_as_taggable_on gem and would like to add a method to one of the gem source files (tag.rb), but I do not want to change the gem source in any way.

I have tried creating my own tag.rb file to in the /app/models directory or in the /lib directory, and then adding the desired method to that file expecting that ruby will merge the two tag.rb files

But when I do I get a NoMethodError: undefined method ...

What am I missing?

解决方案

I think you're right that reopening the Tag class is the way to go. I wouldn't introduce another level of inheritance unless it really made sense for your code.

I'm not sure, off the top of my head, why reopening the Tag class didn't work. A few thoughts:

1 - When you wrote your own Tag class, did it descend from ActiveRecord::Base? The Tag class in acts as taggable on does, and I could see how neglecting that might mess things up.

2 - If I needed a place to put code that reopened a plugin class for a single method, I'd probably put it in an initializer file (such as config/initializers/tag_patch.rb). Just to keep things clean.

3 - If all else fails and you still can't get the Tag class reopened properly (for whatever reason) there are other metaprogramming techniques you might try to add the method. For example:

Tag.send(:define_method, "method_name") do 
  #code for your method
end

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