Training:Bootcamp:Chapter 9

This is Chapter 9. Here is the first part, Chapter 1, or see Chapter 8 (the previous chapter)

Video 9: Inheritance and Statemachines

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Steps 265 - 301 Introduction Aligning items Inheritance Abstract classes Repetition Statemachines Triggers and entry Guards Class actions for triggers Web application example

Chapter 9: Inheritance and Statemachines

In this chapter, we introduce UML inheritance and UML Statemachines.

265. Remove the 20-pixel margin on the buttons and apply the Align Items property end instead, to make everything end up on the bottom line.

266. Test out combinations of Justify content and Align Items, and determine how to familiarize yourself with ways to control the flow of UI widgets.

267. Introduce the new class CarDealer.

268. Introduce the new class CarOwner.

269. Add generalization arrows from CarDealer to CarOwner and from Person to CarOwner.

270. Add the Attribute Name:String to CarOwner and save.

• Notice the error.
• Make sure you understand why Name is reported as a doublet.
• Fix it by removing Name of Person.

271. Move the multi-link association existing between the classes Car and Person (The one with the HistoricOwnership association class) to Car and CarOwner.

• Rename the Car association end from CarsPersonUsedToOwn to CarsOwnerUsedToOwn and apply changes.
• Notice the errors.
• Create and refresh autoforms to correct the errors.
• Select the class CarOwner and mark it as Abstract by going to the Property Inspector and selecting True from the IsAbstract dropdown. Notice now that the label on the CarOwner Class is now in italics.

Make sure you understand Subclass and Superclass. Look up and read through this article on the Wiki:

• UML_Inheritance

272. Add a new association from CarOwner to Car. Name the Car end as CurrentlyOwnedCars.

273. Delete the old link with the currently owned car. Update the autoforms. Save and check for errors.

274. Delete the Combobox that showed the now-removed currently owned car in the Person form.

275. Add a new class: CarTransferOwnershipDocument, and add a new association from Car(0..1) to CarTransferOwnershipDocument(*)

276. Add an association from CarOwner to CarTransferOwnershipDocument. Call the link DocumentsForSales(*) and Seller(0..1)

277. Add another association from CarOwner to CarTransferOwnershipDocument. Call the link DocumentsForPurchase(*) and Buyer(0..1)

278. Add CarFactory and make it a subclass of CarOwner.

279. Add ScrapYard and make it a subclass of CarOwner.

280. Add a statemachine on Class Car.

281. Add a state in the statemachine of the car called BrandNew.

282. Add another state: InOwnershipTransaction.

283. Add a Transition arrow from BrandNew to InOwnershipTransaction.

284. Call the trigger of the transition InitiateSale.

285. Add yet another state called OwnershipStable.

286. Add a transition from InOwnershipTransaction to OwnershipStable. Name the trigger CloseSale.

287. Add a transition from OwnershipStable to InOwnershipTransaction. Reuse the trigger InitiateSale on this transition.

288. Create an Entry Action in the state InOwnerShipTransaction.

• Click the InOwnerShipTransaction state to highlight it's Properties.
• In the Property Inspector click the three dots at the Entry Property to access the Action Editor Entry for InOwnerShipTransaction.
• Type the following Expression:

let doc=CarTransferOwnershipDocument.Create in
(
self.CarTransferOwnershipDocuments.Add(doc);
doc.Seller:=self.CarOwner
)

The Expression above:  

• Creates a CarTransferOwnershipDocument and adds it to the cars list of CarTransferOwnershipDocuments.

• Also, assigns the Seller of the new CarTransferOwnershipDocument to the current owner of the Car.

289. Add an association from CarTransferOwnershipDocument to Car. Call the single-end CurrentTransaction. Set the Car's end to not Navigable.

290. In the Entry Action, in the state InOwnerShipTransaction, assign the CurrentTransaction to the created document.

• Type the following Expression to achieve this :

let doc=CarTransferOwnershipDocument.Create in
(
self.CarTransferOwnershipDocuments.Add(doc);
doc.Seller:=self.CarOwner;
self.CurrentTransaction:=doc
)

291. Go to Guard of CloseSale and check that the current transaction has a Buyer.

• Type the following Expression into the Guard OCL Editor to achieve this :

self.CurrentTransaction.Buyer->notempty

292. In the OwnershipStable, add an Entry action that removes the Car from Seller's CurrentlyOwnedCars and adds it to the Buyer's CurrentlyOwnedCars.

• Type the following Expression to achieve this :

self.CurrentTransaction.Seller.CurrentlyOwnedCars.Remove(self);
self.CurrentTransaction.Buyer.CurrentlyOwnedCars.Add(self)

293. In the OwnershipStable, add an Entry action and add an update of the Seller's CarsOwnerUsedToOwn.

• Update the previous Expression in step 292 as provided below :

self.CurrentTransaction.Seller.CurrentlyOwnedCars.Remove(self);
self.CurrentTransaction.Buyer.CurrentlyOwnedCars.Add(self);
self.CurrentTransaction.Seller.CarsOwnerUsedToOwn.Add(self)

294. On the transition between BrandNew and InOwnerShipTransaction, add a guard that checks that there is a CarOwner.

• Type the following Expression into the OCL Editor Guard BrandNew->InOwnershipTransaction to achieve this:

self.CarOwner->notempty

295. On the InitiateSale trigger, add a ClassAction for the trigger.

296. On the CloseSale trigger, add a ClassAction for the trigger.

297. Refresh the AutoForms.

298. Save and test on the web.

• Create a CarFactory.
• Call it BMW in Munich.
• Add a Car to this CarFactory.

299. Initiate the Sale and check that you get a CarTransferOwnershipDocument.

300. Assign a buyer in the CarTransferOwnershipDocument, then close the Sale. Check that ownership has switched.

301. Set the default representation of CarOwner to self.Name

Next Chapter

Bootcamp:Chapter 10