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Getting Started

Saving a Snapshot Image

At any time during your work, you can always save the current state of the system in a so-called "snapshot image file", from which the system can recover at a later time.
So, if during your excursion through the system, you are getting thirsty and you need a break, simply leave the system and confirm the saving when asked.

When you later restart smalltalk, it will return to exactly the point where you left off before (try it !).

It is also a good idea to create a snapshot before you try out something dangerous - such as modifying a base system class.

Opening a workspace

For your first excursion into the smalltalk language, you should first learn how to open a workspace window and how to leave the debugger in case you ran into an error (which is quite likely -).

A workspace allows you to enter smalltalk code and execute it (this is also refered to as "immediate execution", since you can typeIn some piece of code and immediately evaluate it).

Select the [-->]workspace item in the Launchers [-->]tools menu for a new workspace.

[Workspace-menu-screenshot]

The above opens a view which looks similar to:

[Workspace-screenshot-1]

You can use workspaces as text scratchpads, as copyBuffers or to evaluate Smalltalk expressions (which is their main use).
Expression evaluation is called "doIt evaluation", or "doIt" for short.

Also, you can evaluate some smalltalk code and have the result printed into the workspace. This operation is called "printIt". In the following, we will refer to both actions as doIt.

DoIts are perfect to try out something quickly; you can evaluate expressions to send messages, without a need to write a program which remains permanently in the system (and has to be removed later).

To execute some smalltalk code, type it into the workspace:

[Workspace-screenshot-2]

select it (using the mouse):

[Workspace-screenshot-3]

and evaluate it with the workspaces middle-button [-->]printIt menu function:

[Workspace-screenshot-4]

the result is displayed in the workspace:

[Workspace-screenshot-5]

There are also keyboard accelerators for the most common operations;
"doIt" is usually bound to "Alt-d" and "printIt" to "Alt-p".
(If these do not seem to work, try the "Ctrl"-key instead of "Alt" )

Finally, a selection is quickly by made by pressing the "ESC" key, which selects the current lines text from the beginning to the current textcursor position. (i.e. a printIt can be done with two keys: "ESC" followed by "printIt")
A list of accelerators is found in "Getting started - Keyboard accelerators".

Like on a piece of paper, you can click-and-type anywhere within the workspace (i.e. you are not forced to type into the last line). Also, any text in the workspace can be selected for doIt evaluation.

Try a few expressions; such as:
(dont care for the smalltalk syntax - the meaning will be explained later)

    1 + 2
    2 sqrt
    Transcript showCR:'hello world'
    Transcript showCR:(2 sqrt)
    (Button label:'hello') open
    Workspace open

Leaving the debugger

Whenever an error is encountered, smalltalk opens a debug window, which displays the state of execution and a walkback list (this shows how you got to the point where the error was detected).
During this introduction, as a beginner, you should probably not care too much for all the information as displayed; instead simply abort whatever operation you started. (we will learn more about the debugger later.)

So, if you get into the debugger while evaluating the following examples, simply press the debuggers abort button (or simply close it) and retry whatever you did (but look for any typing errors - otherwise you may get another debugger)

Do NOT fear the debugger - as opposed to whatever programming experience you might have, the Smalltalk debugger is your best friend and the better programmers actually write most of their program in the debugger !

To get used to the debugger, try the following example (which contains an error by purpose) in a workspace. (if tried from within the document viewer, a confirmation dialog will be shown before the debugger window is actually opened):

    1 / (1 min:0)
In the debugger, press the "abort"-button to leave the erronous execution.
For more information on what is shown in the debugger and how to use it, read "Using the Debugger".


Continue in "Smalltalk basics".


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Copyright © Claus Gittinger Development & Consulting
Copyright © eXept Software AG

<cg@exept.de>

Doc $Revision: 1.17 $ $Date: 1999/08/10 13:05:26 $