Why isn't my class method recognized?

Question

I am trying to understand why my class method was not recognized. Below is my code:

wiki_patch.rb

require_dependency 'wiki_content'

module WikiRecipientPatch
    def self.included(base)
      base.send(:include, InstanceMethods)

      base.class_eval do
        alias_method_chain :recipients, :send_wiki_mail
      end
    end
end

module InstanceMethods
    def self.set_mail_checker(mail)
      @mail_checker = mail
    end
end

Rails.configuration.to_prepare do
  WikiContent.send(:include, WikiRecipientPatch)
end

controller.rb

WikiContent.set_mail_checker(params[:mail_checker_wiki])

I am getting this error:

NoMethodError (undefined method `set_mail_checker' for #<Class:0x4876560>):

Any idea why it happens and what the solution for it is?

Answer 1

You got the idiom slightly wrong.

1. ClassMethods / InstanceMethods modules are supposed to be nested in the "main" module ( WikiRecipientPatch in this case).

2. You are including instance methods, but expecting class methods to somehow arise from this? Surely you meant extend ClassMethods , didn't you?

    module WikiRecipientPatch def self.included(base) base.extend ClassMethods end module ClassMethods def set_mail_checker(mail) 'mail checker' end end end class WikiContent; end WikiContent.send(:include, WikiRecipientPatch) WikiContent.set_mail_checker('whatever') # => "mail checker"