Use cases in the code with AOP
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The document discusses the importance of use cases in code. It provides an example use case class for playing a team game that defines roles, algorithms, and domain objects without mentioning the GUI, persistence, or external API calls. The goal is clean use case code, and aspects like the GUI and persistence can be handled separately through aspect-oriented programming and dependency injection of roles at runtime.
![class PlayerWithFriends
setup: => a role
@friends = []
@invitedFriends = []
@acceptedFriends = []
setInvitedFriends: (facebookUids) =>
for facebookUid in facebookUids
friend = new Friend({facebookUid: facebookUid})
@invitedFriends.push(friend)
setFriends: (friends) =>
@friends = friends
addFriend: (friend) =>
existing = @getFriendByFacebookUid(friend?.facebookUid)
if not existing?
@friends.push(friend)](https://image.slidesharecdn.com/lightningio2012usecases-120722182708-phpapp01/85/Use-cases-in-the-code-with-AOP-22-320.jpg)
Use cases in the code with AOP
- 1. Use cases are important Andrzej Krzywda
- 2. Use cases in the code are even more important
- 3. class PlayTeamGameUseCase constructor: (@game, @player) -> Role(@player, PlayerWithFriends) Role(@game, TeamCompetition) tryToEnterGameArea: () => if @amIEnteringGameFirstTime() if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() @teachPlayerHowToPlay() else #n-th time... if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() if @haveNotYetPickedFavPizzaCountry() @askPlayerToDeclareHisFavPizzaCountry() (more methods here)
- 4. Name class PlayTeamGameUseCase constructor: (@game, @player) -> Role(@player, PlayerWithFriends) Role(@game, TeamCompetition) tryToEnterGameArea: () => if @amIEnteringGameFirstTime() if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() @teachPlayerHowToPlay() else #n-th time... if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() if @haveNotYetPickedFavPizzaCountry() @askPlayerToDeclareHisFavPizzaCountry() (more methods here)
- 5. Name class PlayTeamGameUseCase constructor: (@game, @player) -> Actors Role(@player, PlayerWithFriends) Role(@game, TeamCompetition) tryToEnterGameArea: () => if @amIEnteringGameFirstTime() if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() @teachPlayerHowToPlay() else #n-th time... if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() if @haveNotYetPickedFavPizzaCountry() @askPlayerToDeclareHisFavPizzaCountry() (more methods here)
- 6. Name class PlayTeamGameUseCase constructor: (@game, @player) -> Actors Role(@player, PlayerWithFriends) Role(@game, TeamCompetition) Roles tryToEnterGameArea: () => if @amIEnteringGameFirstTime() if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() @teachPlayerHowToPlay() else #n-th time... if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() if @haveNotYetPickedFavPizzaCountry() @askPlayerToDeclareHisFavPizzaCountry() (more methods here)
- 7. Name class PlayTeamGameUseCase constructor: (@game, @player) -> Actors Role(@player, PlayerWithFriends) Role(@game, TeamCompetition) Roles tryToEnterGameArea: () => if @amIEnteringGameFirstTime() if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() @teachPlayerHowToPlay() Algorithm else #n-th time... if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() if @haveNotYetPickedFavPizzaCountry() @askPlayerToDeclareHisFavPizzaCountry() (more methods here)
- 8. Name class PlayTeamGameUseCase constructor: (@game, @player) -> Actors Role(@player, PlayerWithFriends) Role(@game, TeamCompetition) Roles tryToEnterGameArea: () => if @amIEnteringGameFirstTime() if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() @teachPlayerHowToPlay() Algorithm else #n-th time... if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() uses domain objects if @haveNotYetPickedFavPizzaCountry() @askPlayerToDeclareHisFavPizzaCountry() (more methods here)
- 9. Name class PlayTeamGameUseCase constructor: (@game, @player) -> Actors Role(@player, PlayerWithFriends) Role(@game, TeamCompetition) Roles tryToEnterGameArea: () => if @amIEnteringGameFirstTime() if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() @teachPlayerHowToPlay() Algorithm else #n-th time... if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() uses domain objects if @haveNotYetPickedFavPizzaCountry() @askPlayerToDeclareHisFavPizzaCountry() (more methods here) Nothing about GUI or persistence!
- 10. Where is? • GUI • Persistence • API calls • events
- 11. A clean use case code is the main goal
- 12. AOP + DCI
- 14. AOP gives us method hooks
- 17. class GameUseCaseGlue constructor: (@gameUseCase, @game, @gui) -> execute: () => Around(@gameUseCase, 'tryToEnterGameArea', @checkFbInvitation) After (@gameUseCase, 'tryToEnterGameArea', @showTeamArea) After (@gameUseCase, 'tryToEnterGameArea', @showButtonInviteOrPostPicture) Around(@gameUseCase, 'tellPlayerHeIsPartOfTeam', @showTeamPopup) Around(@gameUseCase, 'askPlayerToLikeFanpage', @showLikePopup) Around(@gameUseCase, 'teachPlayerHowToPlay', @showTutorialPopup) Around(@gameUseCase, 'playerWantsToKnowWinnersWithPrize', @showWinnersPopup) Around(@gameUseCase, 'playerWantsToKnowPrizes', @showPrizesPopup) Around(@gameUseCase, 'askPlayerToDeclareHisFavCountry', @showDeclareCountryPopup) Around(@gameUseCase, 'iAcceptMyFriendInvitationToATeam', @onIAcceptMyFriendInvitationToATeam) Around(@gui, 'inviteClicked', @inviteFriends) # gameUseCase.inviteFriends Around(@gameUseCase, 'inviteFriends', @storeInvitationInTheDB) DB here Glue code
- 19. (still glue code) showTeamPopup: (proceed, friendsInviting) => data = {inviting_friends: friendsInviting} popup = @popupsComponent.showPopup('team_popup', data) popup.onClose => proceed(friendsInviting))
- 20. DCI
- 21. class PlayTeamGameUseCase Use case == context constructor: (@game, @player) -> Role(@player, PlayerWithFriends) Role(@game, TeamCompetition) Roles injected runtime tryToEnterGameArea: () => if @amIEnteringGameFirstTime() if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() data objects interact with @teachPlayerHowToPlay() each other else #n-th time... if @amICommingFromInvitation() @tellPlayerHeIsPartOfTeam() if @haveNotYetPickedFavPizzaCountry() @askPlayerToDeclareHisFavPizzaCountry() (more methods here)
- 22. class PlayerWithFriends setup: => a role @friends = [] @invitedFriends = [] @acceptedFriends = [] setInvitedFriends: (facebookUids) => for facebookUid in facebookUids friend = new Friend({facebookUid: facebookUid}) @invitedFriends.push(friend) setFriends: (friends) => @friends = friends addFriend: (friend) => existing = @getFriendByFacebookUid(friend?.facebookUid) if not existing? @friends.push(friend)
- 23. not only for Single Page Applications
- 24. What use cases are in your project?
- 25. learn more about AOP and DCI and ... Enjoy writing elegant use cases!