How to write code that fits the domain model

#code #ruby #summary #boring #write #surprise #leastsurprise

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https://stanko.io/keep-it-boring-dont-surprise-me-52opnwWR6CBh

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# Code Summary for article
# 
# https://stanko.io/keep-it-boring-dont-surprise-me-52opnwWR6CBh

# part 1/4 : Sample code surprising and simple

PurchaseChargerService(
  purchase: PurchaseBuilderService.new(line_items: line_items).call, 
  form: purchase_form, 
  user: current_user
).call
# Why the code ☝️ is surprising: 
#  > "Nobody expects things like `PurchaseChargerService` and `PurchaseBuilderService` to exist, yet alone that you have to call those in succession with a form object and the current user to make a purchase."


user.purchase(line_items)
    .charge(authorization_code: params[:authorization_code])
# Why the code ☝️ is simple?
#  > "While most people working on a web shop expect that a user can just purchase something, and that a purchase can be charged."


# Part 2/4 : Lesson 1: Embrace the domain you are working with

# "Naming something after what it does and putting it next to the thing it works with tells a story that can help people understand what’s going on"

# Rename (location: app/services/purchase_charger_service.rb)
class PurchaseChargerService; end 

# To (location: app/models/purchases/charger.rb)
module Purchases
  class Charger; end 
end  

# Part 3/4 : Lesson 2: Write code that mimics how people think about the domain

# "If a `User` can purchase line items, then add a `purchase` method to the User model that accepts line items"

class User

  # @return [Purchase]
  def purchase(line_items) 
  end 
end

# Part 4/4: Lesson 3: Extract actions into models to tell a story
# 
# "Don’t create new classes just to keep things DRY. If your model has many small or a single large method that deal with a single action, extract it into its own model."

class Purchase

  # @return [Purchases::Charge]
  def charge(authorization_code:)
    Purchases::Charger.new.call 
  end
end