Automatic benchmarking in IRB (based on irb_callbacks gem code)

irb_benchmark.rb

require 'benchmark'
module IRB
  def self.before_eval
  end
  def self.after_eval
  end
  def self.around_eval(&block)
    @timing = Benchmark.measure do
      block.call
    end
  end
  def self.before_output
  end
  def self.after_output
    puts "=> #{@timing.inspect}"
  end
  def self.around_output
    yield
  end
end

module IRB
  class Irb
    alias original_output_value output_value

    # Add before_output, after_output, and around_output callbacks
    # without damaging original behavior.
    def output_value(*args, &block)
      IRB::before_output
      value = nil
      IRB::around_output do
        value = original_output_value(*args, &block)
      end
      IRB::after_output
      value
    end
  end

  class Context
    alias original_evaluate evaluate
    # Add before_eval, after_eval, and around_eval callbacks
    # without damaging original behavior.
    def evaluate(*args, &block)
      IRB::before_eval
      value = nil
      IRB::around_eval do
        value = original_evaluate(*args, &block)
      end
      IRB::after_eval
      value
    end
  end
end