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Recovering from a Crash

In order to get confidence in the way Smalltalk works, you should try the following right now !

Lets assume, that you messed up the system. This can be done by changing one of the elementary system classes (for example, by adding buggy code) or by removing some heavily required component (for example, by nilling a global), or when you "enhance" a heavily used component such as the scrollbar or the text editor.

Lets also assume, that you forgot to save a snapshot image recently. This means, that you either have no snapshot at all, or the existing snapshot is old (typically, a few hours).

To recover from such a situation, you have to start ST/X (with the newest snapshot available) and then reapply individual changes (up to, but excluding any of the "bad ones") via the ChangesBrowser.

To try this in the real world, perform the following steps:

We did the above, to give you a good and warm feeling of safety, your work is not lost, even if ST/X crashes within a coding session. However, how often does such a situation arise in the real world ?
The answer is: very very seldom. Over the years, the system has become quite mature, even with respect to severe errors. Systems typically run for weeks or months with heavy coding going on. If you keep away from system classes (such as Array or all of the GUI classes which the system itself uses), you can easily live for a very long time in an image.
Continue in "Deploying an Application".

Copyright © 1996 Claus Gittinger Development & Consulting
Copyright © eXept Software AG

<cg at exept.de>

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