use Structs instead of long class definitions

invoice.rb

@@ -21,35 +21,17 @@ OptionParser.new do |opts|
   end
 end.parse!
 
-class Transaction
-  def initialize(time, person, product, amount: 1)
-    @time = time
-    @person = person
-    @product = product
-    @amount = amount
-  end
-  
-  attr_accessor :time, :person, :product, :amount
-end
-
-class Product
-  def initialize(id, description, price)
-    @id = id
-    @description = description
-    @price = price
-  end
-
+Transaction = Struct.new(:time, :person, :product, :amount)
+Product = Struct.new(:id, :description, :price) do
   def to_s
-    "#{@id} => #{@description}, #{@price}"
+    "#{id} => #{description}, #{price}"
   end
-  
-  attr_accessor :id, :description, :price
 end
 
 def read_file(file)
   rows = Array.new
   CSV.foreach(file, col_sep: ';', converters: :float) do |row|
-    rows << Transaction.new(row[0],row[1],row[2],amount: row[3])
+    rows << Transaction.new(row[0],row[1],row[2],row[3])
   end
   rows
 end
@@ -59,7 +41,7 @@ def read_db(db)
   db.query("SELECT * FROM Transactions").each do |trans|
     if date_of_prev('monday').to_time < trans["time"]
       transactions << Transaction.new(trans["time"], trans["buyer"],
-                          trans["product"], amount: trans["amount"])
+                          trans["product"], trans["amount"])
     end
   end
   return transactions
@@ -128,8 +110,6 @@ def generate_receipt(persons,draft)
   end
 end
 
-# Utility
-
 def date_of_next(day)
   date  = Date.parse(day)
   delta = date > Date.today ? 0 : 7