improving code readability: abstractions

after.rb

#=> better code (hiding implementation details with abstractions)
STATUS_EMPTY_CART = Status.new(false, "empty cart") 
STATUS_PRODUCTS_UNAVAILABLE = Status.new(false, "some products are unavailable")
STATUS_INSUFFICIENT_MONEY = Status.new(false, "not enough money")
STATUS_SUCCESS = Status.new(true, nil) 

def check_out(current_user)
  cart = current_user.cart

  return STATUS_EMPTY_CART if is_cart_empty(cart)

  return STATUS_PRODUCTS_UNAVAILABLE if are_products_unavailable(cart)

  return STATUS_INSUFFICIENT_MONEY if \
    has_insufficient_money(balance: current_user.balance, 
                           total_price: cart.total_price)

  current_user.deduct_balance(total_price)

  return STATUS_SUCCESS
end

private

def is_cart_empty(cart)
  return cart.count == 0
end

def are_products_unavailable(cart)
  return cart.are_products_available
end

def has_insufficient_money(balance:, total_price:)
  return balance < total_price
end

before.rb

#=> meh code
def check_out(current_user)
  cart = current_user.cart

  if cart.count == 0
    return Status.new(false, "empty cart")
  end

  if cart.are_products_unavailable
    return Status.new(false, "some products are unavailable")
  end

  if current_user.balance < cart.total_price
    return Status.new(false, "not enough money")
  end

  current_user.deduct_balance(total_price)

  return Status.new(true, nil) 
end

https://adriangohjw.github.io/posts/2020/08/02/readability-through-abstraction.html