Is there a hook similar to Class#inherited that's triggered only after a Ruby class definition?

Question

#inherited is called right after the class Foo statement. I want something that\'ll run only after the end statement that closes the c

Answer 1

Use TracePoint to track when your class sends up an :end event.

This module will let you create a self.finalize callback in any class.

module Finalize
  def self.extended(obj)
    TracePoint.trace(:end) do |t|
      if obj == t.self
        obj.finalize
        t.disable
      end
    end
  end
end

Now you can extend your class and define self.finalize, which will run as soon as the class definition ends:

class Foo
  puts "Top of class"

  extend Finalize

  def self.finalize
    puts "Finalizing #{self}"
  end

  puts "Bottom of class"
end

puts "Outside class"

# output:
#   Top of class
#   Bottom of class
#   Finalizing Foo
#   Outside class