"Építő tervminta"

"Ebben a példában autókat szeretnénk összeszereltetni, konkértan Porsche-t, Toyota-t és Ford-ot. A tervmintának megfelelőn van egy absztrakt építőnk, mely 3 különböző féle motort képes megépíteni. A minta Director szerepkörét itt a UI tölti be, ahol egy menü segítségével tudjuk megmondani, hogy az egyes autókat milyen motorral szereljék össze."


Object subclass: #CarBuilder
 instanceVariableNames: 'car'
 classVariableNames: ''
 poolDictionaries: '' 

CarBuilder class>>new
 ^self basicNew initialize 

CarBuilder>>car
 "getter method"
 ^car 

CarBuilder>>car: aCar
 "setter method"
 car := aCar 


CarBuilder subclass: #FordBuilder
 instanceVariableNames: ''
 classVariableNames: ''
 poolDictionaries: '' 

CarBuilder subclass: #ToyotaBuilder
 instanceVariableNames: ''
 classVariableNames: ''
 poolDictionaries: '' 

CarBuilder subclass: #PorscheBuilder
 instanceVariableNames: ''
 classVariableNames: ''
 poolDictionaries: '' 


FordBuilder>>initialize
 self car: FordCar new 

ToyotaBuilder>>initialize
 self car: ToyotaCar new 

PorscheBuilder>>initialize
 self car: PorscheCar new 


CarBuilder>>add4CylinderEngine
  "Do nothing. Subclasses will override." 

FordBuilder>>add4CylinderEngine
 self car addEngine: Ford4CylinderEngine new 

ToyotaBuilder>>add4CylinderEngine
 self car addEngine: Toyota4CylinderEngine new 

PorscheBuilder>>add4CylinderEngine
 self car addEngine: Porsche4CylinderEngine new 


CarBuilder>>addStandard6CylinderEngine
 "Do nothing. Subclasses will override." 

FordBuilder>>addStandard6CylinderEngine
 self car addEngine: FordStandard6CylinderEngine new 

ToyotaBuilder>>addStandard6CylinderEngine
 self car addEngine: ToyotaStandard6CylinderEngine new 

PorscheBuilder>>addStandard6CylinderEngine
 self car addEngine: PorscheStandard6CylinderEngine new 


ViewManager subclass: #CarAssemblerUI
 instanceVariableNames: 'builder'
 classVariableNames: ''
 poolDictionaries: '' 

CarAssemblerUI>>carMenu
"Build the car-manufacturers menu."
 | menu |
 menu := Menu new
  title: 'Car';
  owner: self.
 CarBuilder subclasses do: [:aClass |
  menu
   appendItem: aClass manufacturer "the label"
   selector: (Message "the action"
   receiver: self
   selector: #userChoseBuilder:
   arguments: (Array with: aClass))].
 ^menu 

CarAssemblerUI>>userChoseBuilder: builderClass
 builder := builderClass new. 


CarBuilder class>>manufacturer
 self implementedBySubclass 

FordBuilder class>>manufacturer
 ^'Ford' 

ToyotaBuilder class>>manufacturer
 ^'Toyota' 

PorscheBuilder class>>manufacturer
 ^'Porsche' 


CarAssemblerUI>>engineMenu
  ^Menu new
    title: 'Engine';
    owner: self;
    appendItem: '4-Cylinder'
    selector: #engineIs4Cylinder;
    appendItem: '6-Cylinder Standard' 
    selector: #engineIsStandard6Cylinder;
    appendItem: '6-Cylinder Turbocharged'
    selector: #engineIsTurbocharged6Cylinder;
  yourself 

CarAssemblerUI>>engineIs4Cylinder
"The user has selected the '4-cylinder' menu item
from the 'Engine' pulldown menu. Tell my Builder."
  self builder add4CylinderEngine 

CarAssemblerUI>>engineIsStandard6Cylinder
"The user has selected the 'Standard 6-cylinder'
menu item from the 'Engine' pulldown menu."
 self builder addStandard6CylinderEngine 

CarAssemblerUI>>engineIsTurbocharged6Cylinder
"The user has selected the 'Turbocharged 6-cylinder'
menu item from the 'Engine' pulldown menu."
 self builder addTurbocharged6CylinderEngine 

CarAssemblerUI>>orderCar
"The user has selected the 'Order' menu item, signaling
all car/components selections have been made."
 | completeCar |
 "Get the assembled car from my Builder:"
  completeCar:= builder assembledCar.
 completeCar isNil ifTrue: [^MessageBox message:
  'You haven''t finished assembling a complete car yet!'].
 "Assemble and print an invoice for the assembled car:"
  CarInvoiceMaker new printInvoiceFor: completeCar. 

CarBuilder>>assembledCar
 "Return my final Product after verifying there's
a completed Product to return."
 car isNil ifTrue: [^nil].
 car engine isNil ifTrue: [^nil].
 ^car