Embrace multi-model thinking!

Transcript

1. Embrace multi- model thinking! Ivan Nemytchenko, @inem, 2019
2. • Consulting • Exploring apps architecture • Writing book • Teaching at Goodprogrammer.ru • Gitlabbing • Travelling Ivan Nemytchenko Omsk → Belgrade @inem http://inem.at
3. Rubytrip! 40 days, 4 conferences, 8 countries + 1 meetup! - RubyConfBY Minsk - April 6 - RubyDay Verona - April 11 - RubyWine Kishinev - April 13 - RubyMN - April 29 - RailsConf Minneapolis - April 30 - Saint P RubyConf - June 1-2 railshurts.com/rubytrip
4. railshurts.com/lifecycle
13. What’s missing?
14. Embrace multi- model thinking!
15. ?
16. OOP? Design patterns? SOLID? Functional Programming? DDD? 7 ways to refactor fat models … What should we take into account? Well…
17. What should we take into account? Interaction with external world Applications vs libraries Layered architecture Levels of abstractions REST Domain Driven Design 12 factors Imperative vs Declarative Functional approach Side effects State management Types Polymorphism System thinking
18. State
19. 1.Invited 2.Registered 6.Deleted 3.Banned 5.Expired 4.Promoted User
20. 1.Invited 2.Registered 6.Deleted 3.Banned 5.Expired 4.Promoted User Invoice 1.Created 2.Sent 3.Delivered 4.Paid 5.Expired Task 1.Created 2.Assigned 3.Sheduled 4.Completed 5.Archived
21. The natural way to implement states
22. - if current_organisation_subscribed? %p You are currently subscribed, using the following payment method: %p== #{@org.card_brand}: **** **** **** #{@org.card_last4} %p== Expires #{@org.card_exp_month} / #{@org.card_exp_year} - if @org.last_charge %p== The last payment of $#{@org.last_charge.amount/100} was taken on #{@org.last_charge.created_at.strftime("%d %b % %p== The next payment of $100 is due to be taken on #{(@org.last_charge.created_at + 1.month).strftime("%d %b %Y")} = link_to "Update credit card", edit_subscription_path, class: "btn btn-primary" %p = link_to "Cancel my subscription", subscription_path, method: "DELETE", class: "btn btn-danger", data: {confirm: 'Ar sure?'} - else - if @org.trial_ended? %h2 Thank you for trialing our product %h4 To continue using our product please subscribe to the following plan: - else %h2== Thank you for trialing our product (#{distance_of_time_in_words(@org.created_at, Time.zone.now)} left) %h4 To continue using our product after trial please subscribe to the following plan: %p $100/month %p Up to 500 devices and 200 users %p 3 admin users %p CSV/XLS upload = link_to "Subscribe", new_subscription_path, class: 'btn btn-primary'
23. - if current_organisation_subscribed? #... - if @org.last_charge #... - elsif @org.last_charge_status != 'success' #... #... - if @org.expires_at #... - else - if @org.trial_ended? #... - else #... #...
24. if current_user.active && current_user.account && !current_user.account.deleted && current_org.trial_ends_at > Time.current
25. Every flag doubles the number of states .trial_ended? .expired? .cancelled? .subscription_expired? 4 flags = 16 states!
26. Flags can be hidden dates ranges, associations, status fields - if current_organisation_subscribed? #... - if @org.last_charge #... - elsif @org.last_charge_status != 'success' #... #... - if @org.expires_at #... - else - if @org.trial_ended? #... - else #... #...
27. State Machines
28. State Machines
29. State Machines
30. State Machines
31. gem ‘aasm’ gem ‘state-machines’
32. state_machine :state, initial: :trial do state :trial state :trial_ended state :subscribed state :cancelled_subscription state :not_subscribed state :payment_error event :subscribe do transition [:trial, :not_subscribed, :trial_ended] => :subscribed end event :disable_trial do transition :trial => :trial_ended end event :usage_period_ended do transition :cancelled_subscription => :not_subscribed end #... end
33. - if current_org.trial? #... - elsif current_org.trial_ended? #... - elsif current_org.subscribed? #... - elsif current_org.cancelled_subscription? #... - elsif current_org.payment_error? #... - elsif current_org.not_subscribed? #... render partial: current_org.state
34. def something(org) if org.new_record? # ... 16*2 = 32 states!
35. Control the number of degrees of freedom of your app
36. Painless Rails principles 1.Differentiate 'schema' from 'implementation' 2.Reduce entry point pressure 3.Control the number of degrees of freedom of the app 4.Don't mix layers of abstractions 5.Don't fight against the framework railshurts.com/rails-principles
37. Sources SICP (Structure and Interpretation of Computer Programs) TAPL (Types and Programming Languages) by Benjamin C. Pierce DDD (Domain-driven design) by Eric J. Evans CC2e (Code Complete 2nd edition) by Steve McConnell railshurts.com/rails-principles ISO/IEC/ IEEE 42010 Systems and software engineering — Architecture description
38. railshurts.com
39. railshurts.com Stickers!!