CODEWITHSUNDEEP
ruby
Uri
Uri

Reputation: 2346

How does refinement scope work?

This is essentially a snippet from Ruby Metaprogramming 2. In the section they gloss over this example but there isn't really an explanation.

module MyRefinement
  refine MyClass do
    def my_method
      "refined"
    end
  end
end

class MyClass
  def my_method
    "original"
  end

  def another_method
    my_method
  end
end

using MyRefinement

obj = MyClass.new

puts obj.my_method       #=> "refined"
puts obj.another_method  #=> "original"

Why doesn't the refinement apply when you call my_method from another method?

Upvotes: 4

Views: 594

Answers (2)

Naim Rajiv
Naim Rajiv

Reputation: 3374

refine keyword use to Refinements of the class locally. It's mean we can monkey patch any method by refinement of the class.

In your case, the process of refine/redfined/monkey patch only active when the method get call directly. Also Refinements are lexical in scope. When control is transferred outside the scope the refinement is deactivated.

To get better insight, read the scope part of refinements from here: Refinements

Upvotes: 1

Dave Newton
Dave Newton

Reputation: 160170

It avoids "leaky" refinements, e.g., the refinement applies specifically to the method you refine.

http://yehudakatz.com/2010/11/30/ruby-2-0-refinements-in-practice/

Very near the bottom this functionality is explained; nutshell:

[the] refinement should not leak [...]. If it did, it would mean that any call into any method could leak a refinement into that method, which is the opposite of the purpose of the feature.

Upvotes: 3

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