Workshop Sul Refactoring Agile Day 2008

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Fabiana Romagnoli , Tommaso Torti

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Workshop Sul Refactoring Agile Day 2008

  1. 1. Refactoring di codice legacy Fabiana Romagnoli Tommaso Torti
  2. 2. Refactoring: definizione “Refactoring is the process of changing a software system in such a way that it does not alter the external behavior of the code yet improves its internal structure.” Martin Fowler
  3. 3. I principi del refactoring: • Migliorare il design del codice • Eliminare le duplicazioni (ridurre la quantità di codice) • Rendere il codice più leggibile e facile da modificare
  4. 4. package com.sourcesense.refactoring.workshop; import java.util.Iterator; import java.util.List; public class CaloriesCalculator { private List<Food> foods; private final Person person; public CaloriesCalculator(Person person, List<Food> foods) { this.person = person; this.foods = foods; } public String result() throws Exception { String string = quot;Diet Report for quot; + person.getName() +quot;:nquot;; double cal = 0.0; for (int i = 0; i < foods.size(); i++) { Food food = foods.get(i); string += food.name + quot; - quot; + food.kg + quot;nquot;; if (quot;quot;.equalsIgnoreCase(food.name)) throw new FirstException(); if (quot;applequot;.equals(food.name)) cal += food.kg * 15 * 10; if (quot;magicPillquot;.equals(food.name)) cal -= 10; if (quot;candyquot;.equals(food.name)) cal += food.kg; } string += quot;Total: quot; + cal + quot; kcalnquot;; string += quot;kilometers to be run: quot; + 90 /* calories in one kilometer */ * person.size() / cal; for (Iterator iterator = foods.iterator(); iterator.hasNext();) { Food type = (Food) iterator.next(); if (quot;quot;.equalsIgnoreCase(type.name)) throw new FirstException(); if (person.getKg() > 1000) throw new SecondException(); } return string; } }
  5. 5. Le regole: • Tempo a disposizione: 20 minuti • I test devono restare verdi • I test non possono essere modificati. (Ad esempio non puoi modificare i parametri di input e output, mentre puoi creare nuovi oggetti usati “internamente”
  6. 6. Magic numbers public String result() throws Exception { String string = quot;Diet Report for quot; + person.getName() +quot;:nquot;; double cal = 0.0; for (int i = 0; i < foods.size(); i++) { Food food = foods.get(i); string += food.name + quot; - quot; + food.kg + quot;nquot;; if (quot;quot;.equalsIgnoreCase(food.name)) throw new FirstException(); if (quot;applequot;.equals(food.name)) cal += food.kg * 15 * 10; if (quot;magicPillquot;.equals(food.name)) cal -= 10; if (quot;candyquot;.equals(food.name)) cal += food.kg; } string += quot;Total: quot; + cal + quot; kcalnquot;; string += quot;kilometers to be run: quot; + 90 /* calories in one kilometer */ * person.size() / cal; for (Iterator iterator = foods.iterator(); iterator.hasNext();) { Food type = (Food) iterator.next(); if (quot;quot;.equalsIgnoreCase(type.name)) throw new FirstException(); if (person.getKg() > 1000) throw new SecondException(); } return string; } }
  7. 7. Uso delle costanti parziale public Person(String name, int kg) { this.name = name; this.kg = kg; } public String getName() { return name; } public int getKg() { return kg; } } public int size() { if (kg > 130) return 3; if (kg < 50) return 1; return MEDIUM_SIZE; }
  8. 8. Nomi di variabili metodi e classi public String result() throws Exception { String string = quot;Diet Report for quot; + person.getName() +quot;:nquot;; double cal = 0.0; for (int i = 0; i < foods.size(); i++) { Food food = foods.get(i); string += food.name + quot; - quot; + food.kg + quot;nquot;; if (quot;quot;.equalsIgnoreCase(food.name)) throw new FirstException(); if (quot;applequot;.equals(food.name)) cal += food.kg * 15 * 10; if (quot;magicPillquot;.equals(food.name)) cal -= 10; if (quot;candyquot;.equals(food.name)) cal += food.kg; } string += quot;Total: quot; + cal + quot; kcalnquot;; string += quot;kilometers to be run: quot; + 90 /* calories in one kilometer */ * person.size() / cal; for (Iterator iterator = foods.iterator(); iterator.hasNext();) { Food type = (Food) iterator.next(); if (quot;quot;.equalsIgnoreCase(type.name)) throw new FirstException(); if (person.getKg() > 1000) throw new SecondException(); } return string; } }
  9. 9. Cicli for public String result() throws Exception { String string = quot;Diet Report for quot; + person.getName() +quot;:nquot;; double cal = 0.0; for (int i = 0; i < foods.size(); i++) { Food food = foods.get(i); string += food.name + quot; - quot; + food.kg + quot;nquot;; if (quot;quot;.equalsIgnoreCase(food.name)) throw new FirstException(); if (quot;applequot;.equals(food.name)) cal += food.kg * 15 * 10; if (quot;magicPillquot;.equals(food.name)) cal -= 10; if (quot;candyquot;.equals(food.name)) cal += food.kg; } string += quot;Total: quot; + cal + quot; kcalnquot;; string += quot;kilometers to be run: quot; + 90 /* calories in one kilometer */ * person.size() / cal; for (Iterator iterator = foods.iterator(); iterator.hasNext();) { Food type = (Food) iterator.next(); if (quot;quot;.equalsIgnoreCase(type.name)) throw new FirstException(); if (person.getKg() > 1000) throw new SecondException(); } return string; } }
  10. 10. Responsabilità 1. Costruzione del report ... public String result() throws Exception { String string = quot;Diet Report for quot; + person.getName() +quot;:nquot;; double cal = 0.0; for (int i = 0; i < foods.size(); i++) { Food food = foods.get(i); string += food.name + quot; - quot; + food.kg + quot;nquot;; if (quot;quot;.equalsIgnoreCase(food.name)) throw new FirstException(); if (quot;applequot;.equals(food.name)) cal += food.kg * 15 * 10; if (quot;magicPillquot;.equals(food.name)) cal -= 10; if (quot;candyquot;.equals(food.name)) cal += food.kg; } string += quot;Total: quot; + cal + quot; kcalnquot;; string += quot;kilometers to be run: quot; + 90 /* calories in one kilometer */ * person.size() / cal; for (Iterator iterator = foods.iterator(); iterator.hasNext();) { Food type = (Food) iterator.next(); if (quot;quot;.equalsIgnoreCase(type.name)) throw new FirstException(); if (person.getKg() > 1000) throw new SecondException(); } return string; } }
  11. 11. Responsabilità 2. Calcolo delle calorie ... public String result() throws Exception { String string = quot;Diet Report for quot; + person.getName() +quot;:nquot;; double cal = 0.0; for (int i = 0; i < foods.size(); i++) { Food food = foods.get(i); string += food.name + quot; - quot; + food.kg + quot;nquot;; if (quot;quot;.equalsIgnoreCase(food.name)) throw new FirstException(); if (quot;applequot;.equals(food.name)) cal += food.kg * 15 * 10; if (quot;magicPillquot;.equals(food.name)) cal -= 10; if (quot;candyquot;.equals(food.name)) cal += food.kg; } string += quot;Total: quot; + cal + quot; kcalnquot;; string += quot;kilometers to be run: quot; + 90 /* calories in one kilometer */ * person.size() / cal; for (Iterator iterator = foods.iterator(); iterator.hasNext();) { Food type = (Food) iterator.next(); if (quot;quot;.equalsIgnoreCase(type.name)) throw new FirstException(); if (person.getKg() > 1000) throw new SecondException(); } return string; } }
  12. 12. Responsabilità 3.Validazione ... public String result() throws Exception { String string = quot;Diet Report for quot; + person.getName() +quot;:nquot;; double cal = 0.0; for (int i = 0; i < foods.size(); i++) { Food food = foods.get(i); string += food.name + quot; - quot; + food.kg + quot;nquot;; if (quot;quot;.equalsIgnoreCase(food.name)) throw new FirstException(); if (quot;applequot;.equals(food.name)) cal += food.kg * 15 * 10; if (quot;magicPillquot;.equals(food.name)) cal -= 10; if (quot;candyquot;.equals(food.name)) cal += food.kg; } string += quot;Total: quot; + cal + quot; kcalnquot;; string += quot;kilometers to be run: quot; + 90 /* calories in one kilometer */ * person.size() / cal; for (Iterator iterator = foods.iterator(); iterator.hasNext();) { Food type = (Food) iterator.next(); if (quot;quot;.equalsIgnoreCase(type.name)) throw new FirstException(); if (person.getKg() > 1000) throw new SecondException(); } return string; } }
  13. 13. Validazione: posizione e ripetizione public String result() throws Exception { String string = quot;Diet Report for quot; + person.getName() +quot;:nquot;; double cal = 0.0; for (int i = 0; i < foods.size(); i++) { Food food = foods.get(i); string += food.name + quot; - quot; + food.kg + quot;nquot;; if (quot;quot;.equalsIgnoreCase(food.name)) throw new FirstException(); if (quot;applequot;.equals(food.name)) cal += food.kg * 15 * 10; if (quot;magicPillquot;.equals(food.name)) cal -= 10; if (quot;candyquot;.equals(food.name)) cal += food.kg; } string += quot;Total: quot; + cal + quot; kcalnquot;; string += quot;kilometers to be run: quot; + 90 /* calories in one kilometer */ * person.size() / cal; for (Iterator iterator = foods.iterator(); iterator.hasNext();) { Food type = (Food) iterator.next(); if (quot;quot;.equalsIgnoreCase(type.name)) throw new FirstException(); if (person.getKg() > 1000) throw new SecondException(); } return string; } }
  14. 14. Accesso ai field privati public String result() throws Exception { String string = quot;Diet Report for quot; + person.getName() +quot;:nquot;; double cal = 0.0; for (int i = 0; i < foods.size(); i++) { Food food = foods.get(i); string += food.name + quot; - quot; + food.kg + quot;nquot;; if (quot;quot;.equalsIgnoreCase(food.name)) throw new FirstException(); if (quot;applequot;.equals(food.name)) cal += food.kg * 15 * 10; if (quot;magicPillquot;.equals(food.name)) cal -= 10; if (quot;candyquot;.equals(food.name)) cal += food.kg; } string += quot;Total: quot; + cal + quot; kcalnquot;; string += quot;kilometers to be run: quot; + 90 /* calories in one kilometer */ * person.size() / cal; for (Iterator iterator = foods.iterator(); iterator.hasNext();) { Food type = (Food) iterator.next(); if (quot;quot;.equalsIgnoreCase(type.name)) throw new FirstException(); if (person.getKg() > 1000) throw new SecondException(); } return string; } }
  15. 15. Riferimenti: • Refactoring: Improving the Design of Existing Code - Martin Fowler • Refactoring To Patterns - Joshua Kerievsky
  16. 16. Riferimenti: • Refactoring Workbook - William Wake • Working Effectively With Legacy Code - Michael Feathers

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