Slides from my http://lightning.io talk in Poznan.

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

13. Aspect Oriented
Programming

14. AOP gives us
method hooks

15. After, Before, Around

16. GUI & persistence

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

18. Around(@gameUseCase, 'tellPlayerHeIsPartOfTeam', @showTeamPopup)

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!