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Stoop sed-class initialization
Stoop sed-class initialization
Stoop sed-class initialization
Stoop sed-class initialization
Stoop sed-class initialization
Stoop sed-class initialization
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Stoop sed-class initialization

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  • 1. Stéphane Ducasse 1 Stéphane Ducasse stephane.ducasse@inria.fr http://stephane.ducasse.free.fr/ Elements of Design - Class initialization Class initialization
  • 2. S.Ducasse 2 Class Methods - Class InstanceVariables Classes (Packet class) represents class (Packet). Class instance variables are instance variables of class They should represent the state of class: number of created instances, number of messages sent, superclasses, subclasses.... Class methods represent class behavior: instance creation, class initialization, counting the number of instances.... If you weaken the second point: class state and behavior can be used to define common properties shared by all the instances
  • 3. S.Ducasse 3 Class Initialization How do we know that all the class behavior has been loaded? At the end ! Automatically called by the system at load time or explicitly by the programmer. Used to initialize a classVariable, a pool dictionary or class instance variables. ‘Classname initialize’ at the end of the saved files in Squeak In postLoadAction: inVW
  • 4. S.Ducasse 4 Example of class initialization Magnitude subclass: #Date instanceVariableNames: 'day year' classVariableNames: 'DaysInMonth FirstDayOfMonth MonthNames SecondsInDay WeekDayNames’
  • 5. S.Ducasse 5 Date class>>initialize Date class>>initialize "Initialize class variables representing the names of the months and days and the number of seconds, days in each month, and first day of each month. " MonthNames := #(January February March April May June July August September October November December ). SecondsInDay := 24 * 60 * 60. DaysInMonth := #(31 28 31 30 31 30 31 31 30 31 30 31 ). FirstDayOfMonth := #(1 32 60 91 121 152 182 213 244 274 305 335 ). WeekDayNames := #(MondayTuesday WednesdayThursday Friday Saturday Sunday )
  • 6. S.Ducasse 5 Date class>>initialize Date class>>initialize "Initialize class variables representing the names of the months and days and the number of seconds, days in each month, and first day of each month. " MonthNames := #(January February March April May June July August September October November December ). SecondsInDay := 24 * 60 * 60. DaysInMonth := #(31 28 31 30 31 30 31 31 30 31 30 31 ). FirstDayOfMonth := #(1 32 60 91 121 152 182 213 244 274 305 335 ). WeekDayNames := #(MondayTuesday WednesdayThursday Friday Saturday Sunday )

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