Smalltalk and Object Orientation: an Introduction - Free

Class categories. These are group s of classes which are categorized for convenience. One of these
categories may be selected (as in the figure); the classes in this category are then
presented in the next subview.
Class Names. Classes in the selected c ategory are presented. One of these classes may be selected
(for example, the class object is selected); various categories of messages are then
presented in the next subview.
Message categories. These are the categories of messages which c an be sent to either instances of
the selected class ( instance selected) or to the class itself ( class selected). One of these
categories may be selected; all message selectors in this category are presented in the
right-most subview.
These message categories are also known as protocols. In the reminder of the chapters we shall refer to
this window (pane) as containing protocols and thus it is the protocol window.
Message Selectors . All of the message selectors (essentially method names) i n the protocol are
presented. One of these messages may be selected, its method (the code executed when
this message is received) will be shown in the lower (code view) area. For example, in
Figure 4.3 the isNil message is selected.
The code view window. This window is used to browse and define classes, write methods etc.
You will find that off the right mouse button (if you have a three mouse button then it is the middle
button) each window will produ ce a different menu. These are the window specific menus. You will
make extensive use of them, so get familiar with what is on each menu. Figure 4.4 illustrates each of the
menus for each of the five different windows.
Category Class Protocol Message Code
Figure 4.4: The System Browser Menus
There are a number of other browsers and inspectors in the Smalltalk system, for example the
Protocol Brows er and the Method Browser . They are condensed versions of the System Browser
which possess specific views onto the class hierarchy or onto a particular class. If you have obtained the
advanced programmer’s tools with VisualWorks you will also be able to us e the Full Browser. This is
an excellent browser which possesses a few more features than the basic system browser.
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