noisy-proxy.rb

require 'time' # Time#iso8601

# A NoisyProxy will log all method calls on the wrapped object and their results to the given IO.
# It will optionally _infect_ any object returned by the real method.
class NoisyProxy < BasicObject
  def initialize(inner, infect:false, io:$stderr)
    @inner = inner
    @infect = infect
    @io = io
  end

  def method_missing(method_name, *arguments, &block)
    start = ::Time.now
    @io.write "[#{start.iso8601(9)}] (#{@inner})\##{method_name}(#{arguments.map(&:inspect).join(',')})"
    @io.write '{ ... }' unless block.nil?

    result = @inner.send(method_name, *arguments, &block)

    @io.puts(" #=> #{result} (#{(::Time.now - start).truncate(9)}s)" )

    @infect ? NoisyProxy.new(result, io: @io, infect: @infect) : result
  rescue => e
    @io.puts(" #!> #{e}")
    raise
  end

  def respond_to_missing?(m)
    @inner.respond_to?(m)
  end
end