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Design Patterns

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Daniel Walig¨®ra
Daniel Walig¨®ra

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Design Patterns Daniel Walig¨®ra Wroc?aw 09/01/2012 1
Bibliography ? Martin Fowler,Patterns of Enterprise Appication Architecture ? Matt Zandstra , PHP5 Objects, Patters, and Practice ? http://www.ustream.tv - New York PHP channel ? Symfony Live Berlin 2012 - https://joind.in/event/view/1114 ? http://scholar.google.pl ? http://pzielinski.com 2
Gang of Four 3
Breakdown Design Patterns by GoF Design Patterns creational structural behavioral - abstract factory - decorator - observer - builder - facade - strategy - prototype - composite - command 4
5
6
Implementation related to the context programming scalability language testable modularity (integration test) time-consuming size of project 7
Design patterns IS NOT related Context IS to the related to the programming programming language language 8
1. 2. Transaction Script class?Hotel?? {??? 3. ????private???? 4. ????????$_gateway; 5. ????public?function?__construct(Data_Access_Gateway?$gateway)???? 6. ????{???? 7. ????????$this->_gateway?=?$gateway;???? 8. ????}???? 9. ?? 10. ????public?function?bookRoom($userId,?$fromDate,?$toDate)???? 11. ????{???? 12. ????????$roomId?=?$this->_gateway->_getRoomIdBetweenDates($fromDate,?$toDate);???? 13. ?? 14. ????????if?(!$roomId)?{???? 15. ????????????return?false;???? 16. ????????}???? 17. ?? 18. ????????$days?=?$this->_getAmountOfDays($fromDate,?$toDate);???? 19. ?? 20. ????????if?($days?<?=?7)?{?? 21. ????????????$price?=?$days?*?100;?? 22. ????????}?else?{??? 23. ????????????$price?=?$days?*?80;?? 24. ????????}?? 25. ?????????? 26. ????????$data?=?array(?? 27. ????????????'userId'?=>?$userId,???? 28. ????????????'roomId'?=>?$roomId,?? 29. ????????????'fromDate'?=>?$fromDate,???? 30. ????????????'toDate'?=>?$toDate,???? 31. ????????????'price'?=>?$price,???? 32. ????????);???? 33. ?? 34. ????????$bookingId?=?$this->_gateway->insert('bookings',?$data);???? 35. ?? 36. ????????return?$bookingId;???? 37. ????}???? 38. }? 9
Transaction Script Advantages: Disadvantages: ? simple procedural model ? difficult to maintenance ? works well with a simple ? code duplication data access layer ? easy implementation of use cases 10
1. Table Module #1 class?Hotel?? 2. {???? 3. ????public?function?__construct(Data_Access_Gateway?$gateway,?Booking?$booking)???? ? ????{???? ? ????????$this->_gateway?=?$gateway;?? ? ????????$this->_booking?=?$booking;?? ? ????}???? ? ?? ? ????public?function?bookRoom($userId,?$fromDate,?$toDate)???? ? ????{???? ? ????????$roomId?=?$this->_booking->getRoomBetweenDates($fromDate,?$toDate);?? ? ?? ? ????????if?(!$roomId)?{???? ? ????????????return?false;???? ? ????????}???? ? ?? ? ????????$days?=?$this->_getAmountOfDays($fromDate,?$toDate);???? ? ?? ? ????????if?($days?<?=?7)?{?? ? ????????????$price?=?$days?*?100;?? ? ????????}?else?{??? ? ????????????$price?=?$days?*?80;?? ? ????????}?? ? ?????????? ? ????????$bookingId?=?$this->_booking- >addBooking($userId,?$roomId,?$fromDate,?$toDate,?$price);???? ? ?? ? ????????return?$bookingId;???? ? ????}???? ? }?? ? ?? 11
Table Module #2 1. class?Booking?? 2. {???? 3. ????public?function?__construct(Data_Access_Gateway?$gateway)???? 4. ????{???? 5. ????????$this->_gateway?=?$gateway;???? 6. ????}?? 7. ?????? 8. ????public?function?getRoomBetweenDates($dateFrom,?$dateTo)?? 9. ????{?? 10.????????return?$this->_gateway->getRoomBetweenDates($dateFrom,?$dateTo);?? 11.????}?? 12.?????? 13.????public?function?addBooking($userId,?$roomId,?$fromDate,?$toDate,?$price)???? 14.????{???? 15.????????$data?=?array(?? 16.????????????'userId'?=>?$userId,???? 17.????????????'roomId'?=>?$roomId,?? 18.????????????'fromDate'?=>?$fromDate,???? 19.????????????'toDate'?=>?$toDate,???? 20.????????????'price'?=>?$price,???? 21.????????);???? 22.?? 23.????????$bookingId?=?$this->_gateway->insert('bookings',?$data);???? 24.?? 25.????????return?$bookingId;???? 26.????}???? 27.}?? 12
Table Module vs Transaction Script Advantages: Disadvantages: ? less duplication ? weak support for polymorphism ? encapsulation ? no support ORM ? more organized and structured code ? easy implementation by technology support 13
Domain Model #1 1. class?Hotel?? 2. {???? 3. ????protected?$_hotelId;?? 4. ????protected?$_rooms;?? 5. ?????? 6. ????public?function?bookRoom(User?$user,?$fromDate,?$toDate)???? 7. ????{???? 8. ????????$room?=?$this->_getRoomBetweenDates($fromDate,?$toDate);?? 9. ?? 10. ????????if?(is_null($room))?{???? 11. ????????????return?false;???? 12. ????????}???? 13. ?? 14. ????????$booking?=?$room->bookRoom(User?$user,?$fromDate,?$toDate);?? 15. ?? 16. ????????return?$booking;???? 17. ????}?? 18. }?? 19. ?? 20. class?Room?? 21. {?? 22. ????protected?$_roomId;?? 23. ????protected?$_bookings?=?array();?? 24. ?????? 25. ????public?function?bookRoom(User?$user,?$fromDate,?$toDate)?? 26. ????{?? 27. ????????$days?=?$this->_getAmountOfDays($fromDate,?$toDate);?? 28. ?????????? 29. ????????if?($days?<?=?7)?{?? 30. ????????????$booking?=?new?Booking($user,?new?ShortBookingStrategy($user,?$days));?? 31. ????????}?else?{??? 32. ????????????$booking?=?new?Booking($user,?new?NormalBookingStrategy($user,?$days));?? 33. ????????}?? 34. ?????????? 35. ????????return?$booking;?? 36. ????}?? 37. }? 14
Domain Model #2 1. class?NormalBookingPriceStrategy?extends?BookingPriceStrategy?? 2. {?? 3. ????public?function?getPrice()?? 4. ????{?? 5. ????????$price?=?$this->_days?*?80;?? 6. ?????????? 7. ????????if?($this->_user->isLoyal())?{?? 8. ????????????$price?=?$price?/?2;?? 9. ????????}?? 10.?????????? 11.????????return?$price;?? 12.????}?? 13.}?? 14.?? 15.class?ShortBookingPriceStrategy?extends?BookingPriceStrategy?? 16.{???? 17.????public?function?getPrice()?? 18.????{?? 19.????????return?$this->_days?*?100;?? 20.????}?? 21.} 15
Domain Model vs Procedural Pattern ? time-consuming implementation Advantages: ? additional patterns Disadvantages: ? prevents logic duplication - ORM ? more code readability - data source ? independence from the data source ? much easier to unit test 16
SUMMARY programming scalability language modularity time-consuming testable size of project (integration test) skill of the developers 17
Don¡¯t be STUPID, GRASP SOLID! 18
Sorry, but your code is STUPID! 19
?S ingleton 1.class?DB? 2.{?? 3.????private static $instance; 4.????public static function getInstance() Dupleton ? 5.????{?? 6.????????if(!isset(self::$instance))?{?? 7.????????????self::$instance?=?new?self;?? 8.????????}?? 9.?????????? 10.????????return?self::$instance;?? 11.????}?? 12.}?? 21 20
?S 1.class?DB? 2. {?? ingleton (ctd) 3. ????private static $instance; ? ????public static function getInstance() ? ????{?? ? ????????if(!isset(self::$instance))?{?? ? ????????????self::$instance?=?new?self;?? ? ????????}?? ? ?????????? ? ????????return?self::$instance;?? ? ????}?? ? }?? ? class Order? ? {?? ? ????protected $db; ? ????public function __construct() ? ????{?? ? ????????$this->db?= DB::getInstance();??????????? ? ????}?? ? } 21
?S ingleton (ctd) 1.class DB? 2. { 3. ????//body 4. } 5.class Order? 6. {?? ? ????protected $db; ? ????public function __construct(DB?$db) ? ????{?? ? ????????$this->db?= $db;??????????? ? ????}?? ? } 22
?T ight Coupling 1.Order::buy(); 1.class House? 2. { 3. ????public function __construct() ? ????{ ? ?????????$this->door?=?new?Door(); ? ?????????$this->window?=?new?Window(); ? ????} ? } 1.class House? 2. { 3. ????public function __construct(Door?$door,?Window? $window) ? ????{ ? ?????????$this->door?=?$door; ? ?????????$this->window?=?$window; ? ????} ? } 23
?U ntestable Code I don¡¯t have a time! 24
?P remature Optimization Never Make Code Faster Than Necessary, Something Important Is Always Lost When You Do 25
?P remature Optimization (ctd) Performance 20% of code problems 26
?I ndescriptive Naming char?*?strpbrk?(?const?char?*,?const?char?*?);? ? 27
?I ndescriptive Naming (ctd) Code is Read Far More Often Than Written 28
?Duplication DRY (Don¡¯t Repeat Yourself!) KISS (Keep It Smile, Stupid!) 29
?S ingleton ?Tight Coupling ?Untestable Code ?P remature Optimization ?I ndescriptive Naming ?Duplication 30
?S ingle Responsibility Principle ?O pen/Closed Principle ?L iskov Substitution Principle ?I nterface Segregation Principle ?Dependency Inversion Principle 31
32
Test Driven- Development 33
Advantages of Design Pattern? ? speed up the development process, ? helps to prevent issues that can cause major problems, ? patterns allow developers to communicate using well-known, well understood names for software interactions 34
EoT Thank You 35

More Related Content

Design Patterns

  • 1. Design Patterns Daniel Walig¨®ra Wroc?aw 09/01/2012 1
  • 2. Bibliography ? Martin Fowler,Patterns of Enterprise Appication Architecture ? Matt Zandstra , PHP5 Objects, Patters, and Practice ? http://www.ustream.tv - New York PHP channel ? Symfony Live Berlin 2012 - https://joind.in/event/view/1114 ? http://scholar.google.pl ? http://pzielinski.com 2
  • 4. Breakdown Design Patterns by GoF Design Patterns creational structural behavioral - abstract factory - decorator - observer - builder - facade - strategy - prototype - composite - command 4
  • 5. 5
  • 6. 6
  • 7. Implementation related to the context programming scalability language testable modularity (integration test) time-consuming size of project 7
  • 8. Design patterns IS NOT related Context IS to the related to the programming programming language language 8
  • 9. 1. 2. Transaction Script class?Hotel?? {??? 3. ????private???? 4. ????????$_gateway; 5. ????public?function?__construct(Data_Access_Gateway?$gateway)???? 6. ????{???? 7. ????????$this->_gateway?=?$gateway;???? 8. ????}???? 9. ?? 10. ????public?function?bookRoom($userId,?$fromDate,?$toDate)???? 11. ????{???? 12. ????????$roomId?=?$this->_gateway->_getRoomIdBetweenDates($fromDate,?$toDate);???? 13. ?? 14. ????????if?(!$roomId)?{???? 15. ????????????return?false;???? 16. ????????}???? 17. ?? 18. ????????$days?=?$this->_getAmountOfDays($fromDate,?$toDate);???? 19. ?? 20. ????????if?($days?<?=?7)?{?? 21. ????????????$price?=?$days?*?100;?? 22. ????????}?else?{??? 23. ????????????$price?=?$days?*?80;?? 24. ????????}?? 25. ?????????? 26. ????????$data?=?array(?? 27. ????????????'userId'?=>?$userId,???? 28. ????????????'roomId'?=>?$roomId,?? 29. ????????????'fromDate'?=>?$fromDate,???? 30. ????????????'toDate'?=>?$toDate,???? 31. ????????????'price'?=>?$price,???? 32. ????????);???? 33. ?? 34. ????????$bookingId?=?$this->_gateway->insert('bookings',?$data);???? 35. ?? 36. ????????return?$bookingId;???? 37. ????}???? 38. }? 9
  • 10. Transaction Script Advantages: Disadvantages: ? simple procedural model ? difficult to maintenance ? works well with a simple ? code duplication data access layer ? easy implementation of use cases 10
  • 11. 1. Table Module #1 class?Hotel?? 2. {???? 3. ????public?function?__construct(Data_Access_Gateway?$gateway,?Booking?$booking)???? ? ????{???? ? ????????$this->_gateway?=?$gateway;?? ? ????????$this->_booking?=?$booking;?? ? ????}???? ? ?? ? ????public?function?bookRoom($userId,?$fromDate,?$toDate)???? ? ????{???? ? ????????$roomId?=?$this->_booking->getRoomBetweenDates($fromDate,?$toDate);?? ? ?? ? ????????if?(!$roomId)?{???? ? ????????????return?false;???? ? ????????}???? ? ?? ? ????????$days?=?$this->_getAmountOfDays($fromDate,?$toDate);???? ? ?? ? ????????if?($days?<?=?7)?{?? ? ????????????$price?=?$days?*?100;?? ? ????????}?else?{??? ? ????????????$price?=?$days?*?80;?? ? ????????}?? ? ?????????? ? ????????$bookingId?=?$this->_booking- >addBooking($userId,?$roomId,?$fromDate,?$toDate,?$price);???? ? ?? ? ????????return?$bookingId;???? ? ????}???? ? }?? ? ?? 11
  • 12. Table Module #2 1. class?Booking?? 2. {???? 3. ????public?function?__construct(Data_Access_Gateway?$gateway)???? 4. ????{???? 5. ????????$this->_gateway?=?$gateway;???? 6. ????}?? 7. ?????? 8. ????public?function?getRoomBetweenDates($dateFrom,?$dateTo)?? 9. ????{?? 10.????????return?$this->_gateway->getRoomBetweenDates($dateFrom,?$dateTo);?? 11.????}?? 12.?????? 13.????public?function?addBooking($userId,?$roomId,?$fromDate,?$toDate,?$price)???? 14.????{???? 15.????????$data?=?array(?? 16.????????????'userId'?=>?$userId,???? 17.????????????'roomId'?=>?$roomId,?? 18.????????????'fromDate'?=>?$fromDate,???? 19.????????????'toDate'?=>?$toDate,???? 20.????????????'price'?=>?$price,???? 21.????????);???? 22.?? 23.????????$bookingId?=?$this->_gateway->insert('bookings',?$data);???? 24.?? 25.????????return?$bookingId;???? 26.????}???? 27.}?? 12
  • 13. Table Module vs Transaction Script Advantages: Disadvantages: ? less duplication ? weak support for polymorphism ? encapsulation ? no support ORM ? more organized and structured code ? easy implementation by technology support 13
  • 14. Domain Model #1 1. class?Hotel?? 2. {???? 3. ????protected?$_hotelId;?? 4. ????protected?$_rooms;?? 5. ?????? 6. ????public?function?bookRoom(User?$user,?$fromDate,?$toDate)???? 7. ????{???? 8. ????????$room?=?$this->_getRoomBetweenDates($fromDate,?$toDate);?? 9. ?? 10. ????????if?(is_null($room))?{???? 11. ????????????return?false;???? 12. ????????}???? 13. ?? 14. ????????$booking?=?$room->bookRoom(User?$user,?$fromDate,?$toDate);?? 15. ?? 16. ????????return?$booking;???? 17. ????}?? 18. }?? 19. ?? 20. class?Room?? 21. {?? 22. ????protected?$_roomId;?? 23. ????protected?$_bookings?=?array();?? 24. ?????? 25. ????public?function?bookRoom(User?$user,?$fromDate,?$toDate)?? 26. ????{?? 27. ????????$days?=?$this->_getAmountOfDays($fromDate,?$toDate);?? 28. ?????????? 29. ????????if?($days?<?=?7)?{?? 30. ????????????$booking?=?new?Booking($user,?new?ShortBookingStrategy($user,?$days));?? 31. ????????}?else?{??? 32. ????????????$booking?=?new?Booking($user,?new?NormalBookingStrategy($user,?$days));?? 33. ????????}?? 34. ?????????? 35. ????????return?$booking;?? 36. ????}?? 37. }? 14
  • 15. Domain Model #2 1. class?NormalBookingPriceStrategy?extends?BookingPriceStrategy?? 2. {?? 3. ????public?function?getPrice()?? 4. ????{?? 5. ????????$price?=?$this->_days?*?80;?? 6. ?????????? 7. ????????if?($this->_user->isLoyal())?{?? 8. ????????????$price?=?$price?/?2;?? 9. ????????}?? 10.?????????? 11.????????return?$price;?? 12.????}?? 13.}?? 14.?? 15.class?ShortBookingPriceStrategy?extends?BookingPriceStrategy?? 16.{???? 17.????public?function?getPrice()?? 18.????{?? 19.????????return?$this->_days?*?100;?? 20.????}?? 21.} 15
  • 16. Domain Model vs Procedural Pattern ? time-consuming implementation Advantages: ? additional patterns Disadvantages: ? prevents logic duplication - ORM ? more code readability - data source ? independence from the data source ? much easier to unit test 16
  • 17. SUMMARY programming scalability language modularity time-consuming testable size of project (integration test) skill of the developers 17
  • 19. Sorry, but your code is STUPID! 19
  • 20. ?S ingleton 1.class?DB? 2.{?? 3.????private static $instance; 4.????public static function getInstance() Dupleton ? 5.????{?? 6.????????if(!isset(self::$instance))?{?? 7.????????????self::$instance?=?new?self;?? 8.????????}?? 9.?????????? 10.????????return?self::$instance;?? 11.????}?? 12.}?? 21 20
  • 21. ?S 1.class?DB? 2. {?? ingleton (ctd) 3. ????private static $instance; ? ????public static function getInstance() ? ????{?? ? ????????if(!isset(self::$instance))?{?? ? ????????????self::$instance?=?new?self;?? ? ????????}?? ? ?????????? ? ????????return?self::$instance;?? ? ????}?? ? }?? ? class Order? ? {?? ? ????protected $db; ? ????public function __construct() ? ????{?? ? ????????$this->db?= DB::getInstance();??????????? ? ????}?? ? } 21
  • 22. ?S ingleton (ctd) 1.class DB? 2. { 3. ????//body 4. } 5.class Order? 6. {?? ? ????protected $db; ? ????public function __construct(DB?$db) ? ????{?? ? ????????$this->db?= $db;??????????? ? ????}?? ? } 22
  • 23. ?T ight Coupling 1.Order::buy(); 1.class House? 2. { 3. ????public function __construct() ? ????{ ? ?????????$this->door?=?new?Door(); ? ?????????$this->window?=?new?Window(); ? ????} ? } 1.class House? 2. { 3. ????public function __construct(Door?$door,?Window? $window) ? ????{ ? ?????????$this->door?=?$door; ? ?????????$this->window?=?$window; ? ????} ? } 23
  • 24. ?U ntestable Code I don¡¯t have a time! 24
  • 25. ?P remature Optimization Never Make Code Faster Than Necessary, Something Important Is Always Lost When You Do 25
  • 26. ?P remature Optimization (ctd) Performance 20% of code problems 26
  • 28. ?I ndescriptive Naming (ctd) Code is Read Far More Often Than Written 28
  • 29. ?Duplication DRY (Don¡¯t Repeat Yourself!) KISS (Keep It Smile, Stupid!) 29
  • 30. ?S ingleton ?Tight Coupling ?Untestable Code ?P remature Optimization ?I ndescriptive Naming ?Duplication 30
  • 31. ?S ingle Responsibility Principle ?O pen/Closed Principle ?L iskov Substitution Principle ?I nterface Segregation Principle ?Dependency Inversion Principle 31
  • 32. 32
  • 34. Advantages of Design Pattern? ? speed up the development process, ? helps to prevent issues that can cause major problems, ? patterns allow developers to communicate using well-known, well understood names for software interactions 34