Smalltalk and Object Orientation: an Introduction - Free

5. A Little Smalltalk
5.1 Introduction
In the last chapter we looked at browsers and the System Transcript, in this chapter we examine
Workspaces and inspectors. Workspaces and inspectors are the next most important tools in the
Smalltalk system. We then consider the debugger , one of the most useful tools available to the
developer. Having looked at all the major development tools you will use (at least for the time being)
you are introduced briefly to the Smalltalk language. You will then use the tools available to write some
Smalltalk.
5.2 The Workspace
Workspaces are a kind of direct interface to the system c ompiler. They act a bit like an editor in that
you can type Smalltalk code into them, and execute that code immediately. You can define temporary
and global variables, create instances of classes, perform arithmetic calculations et c. The only thing you
cannot do is define classes and methods (that must be done in one of the browsers). In the following
figure, the Workspace is being used to calculate the average of a set of numbers.
To compile code within a Workspace you first select the code using the left mouse button. You then
bring up the Workspace operations menu using the right mouse button (if you have a three mouse button
you will use the middle button). This menu is also illustrated in Figure 5.1. The fourth grouping on the
menu contains do it, print it and inspect. The do it and print it operations will compile and execute
the code. do it will merely run the code, while the print it operation will also prin t the result of
executing the last expression selected. The result is left highlighted so that you can delete it with the
delete key if you no longer require it. Try them out and see for yourself. The inspect operation will first
compile the code (if requi red) and then open an inspector (see below) on whatever you currently have
selected. It the system was consistent, this option would be called “inspect it”.
You can have as many Workspaces as you require open, you are not limited to a sin gle Workspace.
Of course on a standard PC or Macintosh screen, you may be limited by space. This highlights another
issue, for developing Smalltalk systems, it is often useful to have as much screen “real estate” as you
can get. Bigger really is better in this case.
Figure 5.1: Using the Workspace
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