模块中的alias_method_chain

Question

I want a module to alias_method_chain a method from the class it is included into. Here is how I wrote it:

module MyModule
  self.included(base)
    base.class_eval do
      alias_method_chain :perform, :chain
    end
  end
  def perform_with_chain(opts)
    #Do some stuffs
    perform_without_chain(opts)
    #Do some other stuffs
  end
end

class SomeClass
  include MyModule
  def perform(opts)
  end
end

but this throws an error since, when the module is included, the perform method is not yet defined in SomeClass :

in `alias_method': undefined method `perform' for class `SomeClass' (NameError)

How should one write this pattern so the alias chain fully works?

Answer 1

Include after perform is defined.

class SomeClass
  def perform(opts)
  end
  include MyModule
end