Decoratable

Provides an easy way to define decorations that add common behaviour to your methods.

Installation

gem install decoratable

Requirements

Decoratable does its magic via Module#prepend, which means:

• MRI (1.9.3 and up) OR

• JRuby 9000

Usage

require "decoratable"

module Retryable
  # All methods defined in this module can decorate methods
  extend Decoratable

  def retryable(tries = 1, options = { on: [RuntimeError] })
    attempt = 0
    # To invoke the original method, simply use `yield`
    yield
  rescue *options[:on]
    attempt += 1
    attempt > tries ? raise : retry
  end
end

module Pryable
  extend Decoratable

  def pryable
    yield
  rescue => e
    require "pry"
    binding.pry
  end
end

module Measurable
  extend Decoratable

  def measurable(logger = Logger.new(STDOUT))
    start = Time.now
    yield
  ensure
    # The decoration has access to the original method
    # args and any block passed in the original method call are also available
    # via __args__ and __block__ respectively
    original_method = __decorated_method__

    method_location, line = original_method.source_location
    marker = "#{original_method.owner}##{original_method.name}[#{method_location}:#{line}]"
    duration = (Time.now - start).round(2)

    logger.info "#{marker} took #{duration}s to run."
  end
end

class Client
  extend Measurable
  extend Pryable
  extend Retryable

  # This method will automatically retry on TimeoutErrors, up to 3 times
  retryable(tries = 3, on: [TimeoutError])
  def get
    …
  end

  # If an error is raised in this method, we'll automatically get a pry session
  # to help us debug it
  pryable
  def post
    …
  end

  # Log the time this method takes to run
  measurable
  def delete
    …
  end
end

Decoratable provides a handful of decorations as part of the gem:

* require "decoratable/countable": keep a count each time a method gets called
* require "decoratable/debuggable": open a Ruby debug console (i.e. require "debug") if an error is raised
* require "decoratable/deprecatable": log a warning whenever a deprecated method gets called; logs the caller's location
* require "decoratable/hintable": add type hinting to your method arguments
* require "decoratable/memoizable": automatically memoize the return value of a method
* require "decoratable/pryable": open a Pry debug console (i.e. binding.pry) if an error is raised
* require "decoratable/retryable": automatically retry a number of times when a specified exception is raised
* require "decoratable/synchronizable": only allow a method to be called once at a time

More to be added as time goes on.