Smalltalk and Object Orientation: an Introduction - Free

12.6 The private-updating protocol
Next we return to the instance side of the class (by selecting the instance radio button in the System
Browser) and define each of the methods in the private-accessing protocol. Remember you MUST move
back to the instance side of the class by selecting the instance radio button below the class list. Notice
that the name of this protocol is comprised of two names “private” and “updating”. This is because, it is
not intended for use by users of this class. Rather it is used by the initialize method to set up an instance
of this class. The methods there are ”private” to the object and are used for “updating” the state of the
object.
The addressBook: method is an updater method for the addressBook instance variable. It is
used to accept a new dictionary object to use for the addressBook. It is intended only for use with
the instance creation method of the Organizer class.
addressBook: aDictionary
addressBook := aDictionary
The appointments: method is an updater method for the appointments instance variable. It is
used to accept a new dictionary object to use for the appointments. It is intended only for use with
the instance creation method of the Organizer class.
appointments: aDictionary
appointments := aDictionary.
Finally, the notes: method gives the notes instance variable a Bag to hold its contents.
notes: aBag
notes := aBag.
Figure 12.5 illustrates the state of the System Full Browser at the end of these steps.
Figure 12.5: The private-updating protocol
12.7 The accessing protocol
Now we will define the methods for the accessing protocol. First define the protocol then each of th e
following methods in turn. We will first define the instance variable accessors and then the Organizer
specific methods. As before, the accessor methods have the same name as the instance variables. We
will also define methods which are used to set the contents of instance variables.
The addNote: method adds a new note to the notes instance variable.
addNote: aNote
notes add: aNote.
The newAddress:for: method is used to add a new address to the address book. It is illustrated
in Figure 12.6.
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