guardable.rb

class Guardable
  def initialize(obj)
    @obj = obj
  end

  def method_missing(method_name, *args, &block)
    return @obj if @obj.nil?

    @obj.send(method_name, *args, &block)
  end
end

module NilGuard
  refine Object do
    def &
      Guardable.new(self)
    end
  end

  refine Array do
    def &
      Guardable.new(self)
    end
  end

  refine NilClass do
    def &
      Guardable.new(self)
    end
  end
end

using NilGuard

p "hoge".&.upcase.&.gsub(/H/, "n")

p %w(foo bar).&.map {|str| nil}.each {|n| n.&.to_i}.compact