Observe Hash#[]=

delegator

class SnakeHash < SimpleDelegator
  def []=(arg1, arg2)
    puts "!!1!"
    @delegate_sd_obj[arg1] = arg2
  end
end

#[2] pry(main)> h = SnakeHash.new(Hash.new)
#=> {}
#[3] pry(main)> h[2]
#=> nil
#[4] pry(main)> h[2] = :foo
#!!1!
#=> :foo

inheritance

class FakeHash < Hash
  def []=(arg1,arg2)
    puts "!!!1!"
    super
  end  
end

#[6] pry(main)> i = FakeHash.new
#=> {}
#[7] pry(main)> i[1]
#=> nil
#[8] pry(main)> i[1] = 3
#!!!1!
#=> 3