Ćwiczenie z refaktoryzacji (na podstawie Refactoring Workbook)

1. Szkolenie dla NaviExpert, 22.02.2011 Ćwiczenie z refaktoryzacji(na podstawie Refactoring Workbook)

2. Agenda Refactoring exercises • simple game example (by W. Wake) • dining philosphers

3. A simple game Rules • the game implements a simplistic example of a tic-tac-toe family • there is a board divided into squares, which are occupied by different markers; every player has different marker ('X' or 'O') • it this case the board is linear and is 9 squares long • given a set and a player marker, the program answers with a move • the winner is the party that lines up a sequence of three markers in a row • the program is to be extended in future

4. A simple game public class Game { public StringBuffer board; public Game(String s) {board = new StringBuffer(s);} public Game(StringBuffer s, int position, char player) { board = new StringBuffer(); board.append(s); board.setCharAt(position, player); } public int move(char player) { for (int i = 0; i < 9; i++) { if (board.charAt(i) == '-') { Game game = play(i, player); if (game.winner() == player) return i; } } for (int i = 0; i < 9; i++) { if (board.charAt(i) == '-') return i; } return -1; }

5. A simple game public Game play(int i, char player) { return new Game(this.board, i, player); } public char winner() { if (board.charAt(0) != '-' && board.charAt(0) == board.charAt(1) && board.charAt(1) == board.charAt(2)) return board.charAt(0); if (board.charAt(3) != '-' && board.charAt(3) == board.charAt(4) && board.charAt(4) == board.charAt(5)) return board.charAt(3); if (board.charAt(6) != '-' && board.charAt(6) == board.charAt(7) && board.charAt(7) == board.charAt(8)) return board.charAt(6); return '-'; } }

6. A simple game int pos = new Game("XOXOX-OXO").move('X'); position gameboard player char winner = new Game("XOXXX-OXO").winner(); winner's marker

7. A simple game Tasks • Identify smells • Suggest refactorings to remove the smells • merge loops • simplify subsequent ifs • name constants appropriately • rework duplicates in winner() method • mark '–' as empty square • replace for loops with iterator • provide extension points for scoring

8. Q&A ?