Posted by Nicola Mingotti on Feb 05, 2020; 3:07am
URL: https://forum.world.st/halt-method-not-halting-execution-tp5111132p5111163.html


Hi,

I never red the book of Robots, but I see a lot of people name it.

Anyhow, here is a simple script that loops over integers and stops
when it reaches the arbitrary number "1567". It stops by opening
a debugger.

In the debugger look for UndefinedObject>>doIt to see your code.

This script is an example of bad code. Indeed it will lock your interface until it finishes its jobs. And, if you look in the Transcript window you will see the counting is going on very very slowly.

But, being so bed is instructive, because you can try to call the debugger with Alt+. (try also Ctrl+. or Cmd+. it depends on the  OS) in cases like this, when the interface gets stuck. Many times you are going to save your session ;)

|i|
i := 0.
[true] whileTrue: [
    i := i + 1.
    (i = 1567) ifTrue: [self halt].
    Transcript ensureCr; show: ('number: {1}' format: {i.}).
    ].


bye
Nicola

All,

I am working my way through the Squeak: Learn Programming with Robots and I hit some unexpected behavior with the halt method in Chapter 15.  I am not at that computer at the moment so cannot say exactly which 3.x version of the VM I am using.  It is using the Ready.image and the V3.sources files.

According to the book, the halt method should cause execution to stop and invoke the debugger.  It does in fact invoke the debugger, however, it also skips past and keeps executing.  Is there by chance some setting somewhere telling the program to skip that method and keep executing?

I can follow-up later tonight with better details, but thought I'd through the question out in case there was in fact an easy answer...

Robert Kuropkat

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