include FooCafe

author = Presenter.new(:buren)
slides = MigratingLegacy::Slides.new

wait until author.ready?

author.present(slides) do |slide|
  print slide
  any_questions? if slide.last?
end

Goto: http://jacobburenstam.com/migrating-legacy

GOTO

jacobburenstam.com/migrating-legacy

Agenda

• Please interupt me!

Disclaimer

• My on personal opinions, not the opinions of my employer.
• Your mileage may vary (a lot)

Jacob Burenstam

• Open source tinkerer
• Useless code enthusiast
• Work @ Trialbee

• github.com/buren
• keybase.io/buren

Legacy code

Definition?

Legacy code has many definitions:

• Code for {outdated|obsolete} systems that is kept for {compatibility|legal|SLA} reasons
• Code written by another person who don't maintain it anymore
• Code without test (Micheal Feathers)

Legacy code in images

Keep it simple stupid!

Legacy code..

"... A large part of the task of a software engineer is to continually alter code to prevent this."

• Wikipedia

Many ways to battle legacy code

• There is no silver bullet
• Be pragmatic, very pragmatic

Michael Feathers on improving legacy code

• Break external dependencies
• Break internal dependencies
• Write tests

Inspiration

"The functional core and the imperative shell"

• Gary Bernhardt

https://www.destroyallsoftware.com/talks/boundaries

Remember the code from the first slide?

include FooCafe

author = Presenter.new(:buren)
slides = MigratingLegacy::Slides.new

wait until author.ready?

author.present(slides) do |slide|
  print slide
  any_questions? if slide.last?
end

DEADLINE = Time.new(2015, 10, 14, 18, 0, 0).freeze
module FooCafe;end
module FooCafe::MigratingLegacy;end
String.class_eval { define_method(:last?) { false } }
NilClass.class_eval { define_method(:last?) { true } }
define_method(:wait) { puts 'Still not ready..';sleep 3 }
define_method(:any_questions?) { puts 'Any questions?' }
define_method(:feedback) { puts 'Feedback?' }
class FooCafe::Presenter < Struct.new(:name)
  define_method(:ready?) { Time.now >= DEADLINE }
  def present(slides); slides.to_a.each { |slide| yield(slide) };end
end
class FooCafe::MigratingLegacy::Slides
  define_method(:initialize) { @slides = File.read('slides.md').split('---') }
  define_method(:to_a) { @slides + [nil] }
end

This actually makes the previous code work

• http://git.io/vnWsf

Slides available on

https://github.com/buren/migrating-legacy

Questions?

github.com/buren

keybase.io/buren

Build your own ingrations?

Use some existing library?

React backend integrations

• Python
  • https://github.com/reactjs/react-python
  • https://github.com/markfinger/python-react
• Meteor
  • https://github.com/reactjs/react-meteor
• Ruby
  • https://github.com/reactjs/react-rails
  • https://github.com/shakacode/reactonrails
• PHP
  • https://github.com/talyssonoc/react-laravel

Lets look at some code