Smalltalk and Object Orientation: an Introduction - Free

28. A Visual Organizer
28.1 Introduction
This chapter presents a VisualWorks version of the Organizer Class described earlier in the book.
That is, a graphical front end is constructed that works with the classes previously constructed. The
organizer was intended as an electronic personal organizer. It therefore possessed an address book, a
diary (or appointments section) and a section for notes. However the version previously described
required the user to send the appropriate messages to an instance of Organizer using the Workspace.
For example, in Figure 28.1 the user has created an instance of Organizer and sent it a variety of
messages which record addresses, appointments and notes. This certainly works, however, the use of a
graphical interface would be preferable. This wo uld allow the user to input the appropriate information
via buttons, input fields and text windows.
Figure 28.1: Using the (non graphical) Organizer
Figure 28.3 illustrates the type of interface to be constructed for the address input window. As can
be seen from this figure, having a graphical user interface (GUI) leads to a far more intuitive interface.
The chapter is structured in the following manner: Section two desc ribes the VisualOrganizer
class which acts as the class used to define the graphical interface, Section three describes the
associated AddressBook class and Section four provides a final comment.
28.2 VisualOrganizer class
In the example in this chapter we are going to construct a graphical version of the Organizer we
constructed earlier in this book. We shall make a number of changes to the architecture of the
Organizer in order to define the VisualOrganizer. The major changes are:
1. The VisualOrganizer class will be a subclass of ApplicationModel rather than Object.
This is because we wish to inherit all the facilities used to manage VisualWorks windows. This is
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