Refactoring in AS3

1. Refactoring in AS3

2. http://blog.eddie.com.tw aquarianboy@ptt [email protected] aquarianboy@plurk eddiekao@facebook

4. AS3 OOP Design Pattern

5. ...

6. Refactoring...?

10. !=

14. duplicated code, long method, large class, long parameter list...

15. If it stinks, change it.

16. Rule of Three Three strikes and you refactor

18. ? ! ...

19. ? ... !

20. ? ... !

21. Design Pattern (over-engineering)

22. Design Pattern v.s. Refactoring

27. .. 1. 2. 3. 2 2 2 1.5 1.5 3 3 1.5 3 1 1 1

28. Extract Method ...

29. // Customer.as // Customer.as public function checkout ():String public function checkout():String { { ... while(rentals.length > 0) while(rentals.length > 0) { { ... ... ... this_amount = amount_for(the_rental); ... switch(the_rental.get_movie().get_price_code()) } { .. case Movie.REGULAR: // } this_amount += 2; if (the_rental.get_days_rented() > 2) private function amount_for (the_rental:Rental):Number { { this_amount+=(the_rental.get_days_rented()-2)* 1.5; var result:int = 0; } switch (the_rental.get_movie().get_price_code()) break; { case Movie.REGULAR :// case Movie.NEW_RELEASE: // result += 2; this_amount += the_rental.get_days_rented() * 3; if (the_rental.get_days_rented() > 2) break; { result += (the_rental.get_days_rented() - 2) * 1.5; case Movie.CHILDRENS: // } this_amount += 1.5; break; if (the_rental.get_days_rented() > 3) { case Movie.NEW_RELEASE :// this_amount+=(the_rental.get_days_rented()-3)*1.5; result += the_rental.get_days_rented() * 3; } break; break; } case Movie.CHILDRENS :// ... result += 1.5; } if (the_rental.get_days_rented() > 3) { result += (the_rental.get_days_rented() - 3) * 1.5; } break; } return result; }

33. Move Method method ...

34. // Customer.as // Customer.as public class Customer public class Customer { { .. private function amount_for (the_rental:Rental):Number private function amount_for (the_rental:Rental):Number { { return the_rental.get_charge(); var result:int = 0; } switch (the_rental.get_movie().get_price_code()) } { case Movie.REGULAR :// // Rental.as result += 2; public class Rental if (the_rental.get_days_rented() > 2) { { ... result += (the_rental.get_days_rented() - 2) * 1.5; public function get_charge():Number } { break; var result:int = 0; switch (get_movie().get_price_code()) case Movie.NEW_RELEASE :// { result += the_rental.get_days_rented() * 3; case Movie.REGULAR :// break; result += 2; if (get_days_rented() > 2) case Movie.CHILDRENS :// { result += 1.5; result += (get_days_rented() - 2) * 1.5; if (the_rental.get_days_rented() > 3) } { break; result += (the_rental.get_days_rented() - 3) * 1.5; } case Movie.NEW_RELEASE :// break; result += get_days_rented() * 3; } break; return result; case Movie.CHILDRENS :// } result += 1.5; .. if (get_days_rented() > 3) } { result += (get_days_rented() - 3) * 1.5; } break; } return result; } ... }

38. // Customer.as // Customer.as public class Customer public class Customer { { .. .. public function checkout ():String public function checkout ():String { { var total_amount:Number = 0;// var total_amount:Number = 0;// var bonus_points:int = 0;// var bonus_points:int = 0;// var rentals:Array = _rentals; var rentals:Array = _rentals; var result:String = get_name() +" n"; var result:String = get_name() +" n"; while (rentals.length > 0) while (rentals.length > 0) { { var this_amount:Number = 0; var this_amount:Number = 0; var the_rental:Rental = rentals.shift() as Rental; var the_rental:Rental = rentals.shift() as Rental; this_amount = amount_for(the_rental); this_amount = the_rental.get_charge(); // // bonus_points += 1; bonus_points += 1; ... ... } } result += "n " + total_amount + "n"; result += "n " + total_amount + "n"; result += " " + bonus_points + " "; result += " " + bonus_points + " "; return result; return result; } } .. .. } }

41. Replace Temp with Query ...

42. // Customer.as // Customer.as public function checkout ():String public function checkout ():String { { var total_amount:Number = 0;// var total_amount:Number = 0;// var bonus_points:int = 0;// var bonus_points:int = 0;// var rentals:Array = _rentals; var rentals:Array = _rentals; var result:String = get_name() +" n"; var result:String = get_name() +" n"; while (rentals.length > 0) while (rentals.length > 0) { { var this_amount:Number = 0; var the_rental:Rental = rentals.shift() as Rental; var the_rental:Rental = rentals.shift() as Rental; // this_amount = amount_for(the_rental); bonus_points += 1; // // 2 1 bonus_points += 1; if ((the_rental.get_movie().get_price_code() == Movie.NEW_RELEASE) && (the_rental.get_days_rented() > 1)) // 2 1 { if ((the_rental.get_movie().get_price_code() == bonus_points += 1; Movie.NEW_RELEASE) && (the_rental.get_days_rented() > 1)) } { result += "-" + the_rental.get_movie().get_title() + " " + bonus_points += 1; the_rental.get_charge() +" n"; } total_amount += the_rental.get_charge(); result += "-" + the_rental.get_movie().get_title() + " " + } this_amount +" n"; total_amount += this_amount; result += "n " + total_amount + "n"; } result += " " + bonus_points + " "; result += "n " + total_amount + "n"; return result; result += " " + bonus_points + " "; } return result; }

45. Extract Method ...

46. // Customer.as // Customer.as public function checkout ():String public function checkout ():String { { ... while (rentals.length > 0) ... { while (rentals.length > 0) var this_amount:Number = 0; { var the_rental:Rental = rentals.shift() as Rental; var this_amount:Number = 0; var the_rental:Rental = rentals.shift() as Rental; this_amount = amount_for(the_rental); this_amount = amount_for(the_rental); // bonus_points += 1; // bonus_points += the_rental.get_bonus_points(); // 2 1 if ((the_rental.get_movie().get_price_code() == result += "-" + the_rental.get_movie().get_title() + " " + Movie.NEW_RELEASE) && (the_rental.get_days_rented() > 1)) this_amount +" n"; { total_amount += this_amount; bonus_points += 1; } } ... } result += "-" + the_rental.get_movie().get_title() + " " + this_amount +" n"; // Rental.as total_amount += this_amount; public class Rental } { ... .. } public function get_bonus_points():int { // 2 1 if ((get_movie().get_price_code() == Movie.NEW_RELEASE) && (get_days_rented() > 1)) { return 2; } else { return 1; } } .. }

50. Replace Temp with Query ...

51. // Customer.as // Customer.as public class Customer public class Customer { { ... public function checkout ():String public function checkout ():String { { var total_amount:Number = 0;// var total_amount:Number = 0;// var bonus_points:int = 0;// var bonus_points:int = 0;// var rentals:Array = _rentals.concat(); var rentals:Array = _rentals.concat(); var result:String = get_name() +" n"; var result:String = get_name() +" n"; while (rentals.length > 0) while (rentals.length > 0) { { var the_rental:Rental = rentals.shift() as Rental; var the_rental:Rental = rentals.shift() as Rental; // // bonus_points += the_rental.get_bonus_points(); bonus_points += the_rental.get_bonus_points(); result += "-" + the_rental.get_movie().get_title() + " " result += "-" + the_rental.get_movie().get_title() + " " + the_rental.get_charge() +" n"; + the_rental.get_charge() +" n"; } total_amount += the_rental.get_charge(); } result += "n " + get_total_charge() + "n"; result += " " + bonus_points + " "; result += "n " + total_amount + "n"; result += " " + bonus_points + " "; return result; } return result; } private function get_total_charge():Number ... { } var rentals:Array = _rentals.concat(); var result:Number = 0; while (rentals.length > 0) { var the_rental:Rental = rentals.shift() as Rental; result += the_rental.get_charge(); } return result; } }

55. // Customer.as // Customer.as public class Customer public class Customer { { .. .. public function checkout ():String public function checkout ():String { { var total_amount:Number = 0;// var total_amount:Number = 0;// var bonus_points:int = 0;// var bonus_points:int = 0;// var rentals:Array = _rentals.concat(); var rentals:Array = _rentals.concat(); var result:String = get_name() +" n"; var result:String = get_name() +" n"; while (rentals.length > 0) while (rentals.length > 0) { { var the_rental:Rental = rentals.shift() as Rental; var the_rental:Rental = rentals.shift() as Rental; // result += "-" + the_rental.get_movie().get_title() + " " bonus_points += the_rental.get_bonus_points(); + the_rental.get_charge() +" n"; } result += "-" + the_rental.get_movie().get_title() + " " + the_rental.get_charge() +" n"; result += "n " + get_total_charge() + "n"; total_amount += the_rental.get_charge(); result += " " + get_total_bonus_points() + " "; } return result; result += "n " + total_amount + "n"; } result += " " + bonus_points + " "; private function get_total_bonus_points():int return result; { } var rentals:Array = _rentals.concat(); .. var result:int = 0; } while (rentals.length > 0) { var the_rental:Rental = rentals.shift() as Rental; result += the_rental.get_bonus_points(); } return result; } .. }

59. Move Method ...

60. // Rental.as // Rental.as public class Rental public class Rental { { ... public function get_charge():Number public function get_charge():Number { { return _movie.get_charge(_days_rented); var result:int = 0; } switch (get_movie().get_price_code()) } { case Movie.REGULAR :// // Movie.as result += 2; public class Movie if (get_days_rented() > 2) { { public function get_charge(days_rented:int):Number result += (get_days_rented() - 2) * 1.5; { } var result:int = 0; break; switch (get_price_code()) { case Movie.NEW_RELEASE :// case Movie.REGULAR :// result += get_days_rented() * 3; result += 2; break; if (days_rented > 2) { case Movie.CHILDRENS :// result += (days_rented - 2) * 1.5; result += 1.5; } if (get_days_rented() > 3) break; { result += (get_days_rented() - 3) * 1.5; case Movie.NEW_RELEASE :// } result += days_rented * 3; break; break; } case Movie.CHILDRENS :// return result; result += 1.5; } if (days_rented > 3) .. { } result += (days_rented - 3) * 1.5; } break; } return result; } }

64. // Rental.as // Rental.as public class Rental public class Rental { { ... .. public function get_bonus_points():int public function get_charge():Number { { // 2 1 return _movie.get_bonus_points(_days_rented); if ((get_movie().get_price_code() == Movie.NEW_RELEASE) && } (get_days_rented() > 1)) .. { } return 2; } // Movie.as else public class Movie { { return 1; .. } public function get_bonus_points(days_rented:int):int } { .. // 2 1 } if ((get_price_code() == Movie.NEW_RELEASE) && (days_rented > 1)) { return 2; } else { return 1; } } .. }

68. Self Encapsulate Field

69. // Movie.as // Movie.as public class Movie public class Movie { { ... ... private var _title:String;// private var _title:String;// private var _price_code:int;// private var _price_code:int;// public function Movie (title:String,price_code:int):void public function Movie (title:String,price_code:int):void { { _title = title; _title = title; _price_code = price_code; set_price_code(price_code); } } ... ... } }

72. Inheritance

73. // Price.as // RegularPrice.as public class Price public class RegularPrice extends Price { { public function get_price_code():int override public function get_price_code():int { { throw new Error("method must be overrided: return Movie.REGULAR; get_price_code"); } } } } // NewReleasePrice.as public class NewReleasePrice extends Price { override public function get_price_code():int { return Movie.NEW_RELEASE; } } // ChildrensPrice.as public class ChildrensPrice extends Price { override public function get_price_code():int { return Movie.CHILDRENS; } }

76. // Movie.as // Movie.as public class Movie public class Movie { { ... ... private var _title:String; // private var _title:String; // private var _price_code:int; // private var _price:Price; // public function get_price_code ():int public function get_price_code ():int { { return _price_code; return _price.get_price_code(); } } public function set_price_code (arg:int):void public function set_price_code (arg:int):void { { _price_code = arg; switch(arg) } { .. case REGULAR: } _price = new RegularPrice(); break; case NEW_RELEASE: _price = new NewReleasePrice(); break; case CHILDRENS: _price = new ChildrensPrice(); break; default: throw new Error("wrong price code"); } } .. }

83. Move Method ...

84. // Movie.as // Movie.as public class Movie public class Movie { { ... public function get_charge (days_rented:int):Number public function get_charge (days_rented:int):Number { { return _price.get_charge(days_rented); var result:int=0; } switch (get_price_code()) } { case Movie.REGULAR :// // Price.as result+= 2; public class Price if (days_rented > 2) { { .. result+= days_rented - 2 * 1.5; public function get_charge (days_rented:int):Number } { break; var result:int=0; switch (get_price_code()) case Movie.NEW_RELEASE :// { result+= days_rented * 3; case Movie.REGULAR :// break; result+= 2; if (days_rented > 2) case Movie.CHILDRENS :// { result+= 1.5; result+= days_rented - 2 * 1.5; if (days_rented > 3) } { break; result+= days_rented - 3 * 1.5; } case Movie.NEW_RELEASE :// break; result+= days_rented * 3; } break; return result; } case Movie.CHILDRENS :// .. result+= 1.5; } if (days_rented > 3) { result+= days_rented - 3 * 1.5; } break; } return result; } .. }

88. Replace Conditional with Polymorphism

89. // Price.as // RegularPrice.as public class Price public class RegularPrice extends Price { { public class Price ... { override public function get_charge (days_rented:int):Number public function get_price_code():int { { var result:Number=2; throw new Error("this method must be override: if (days_rented > 2) get_price_code()"); { } result+= days_rented - 2 * 1.5; } public function get_charge (days_rented:int):Number return result; { } throw new Error("this method must be override: ... days_rented()"); } } } // NewReleasePrice.as } public class NewReleasePrice extends Price { ... override public function get_charge (days_rented:int):Number { return days_rented * 3; } ... } // ChildrensPrice.as public class ChildrensPrice extends Price { ... override public function get_charge (days_rented:int):Number { var result:Number=1.5; if (days_rented > 3) { result+= days_rented - 3 * 1.5; } return result; } ... }

92. // Movie.as // Price.as public class Movie public class Price { { ... .. public function get_bonus_points(days_rented:int):int public function get_bonus_points(days_rented:int):int { { // 2 1 return 1; if (get_price_code() == Movie.NEW_RELEASE && days_rented > } 1) .. { } return 2; } // NewReleasePrice.as else public class NewReleasePrice { { return 1; .. } override public function get_bonus_points } (days_rented:int):int .. { } // 2 1 return (days_rented > 1) ? 2 : 1; } .. }

96. ...

99. Thank You!

Refactoring in AS3

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