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From: James Melhuish <jjms@world.std.com>
Subject: Help: STExpress hangs with 100% CPU usage
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Date: Fri, 10 Jan 1997 20:06:12 GMT
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Hi All,
I am learning Smalltalk with Smalltalk Express 2.0, and I am following
the tutorial step by step.  I have a problem in Tutorial Chapter 9 where
Smalltalk hangs by using 100 percent of CPU time on the execution (Do
It) of the code:
************************
Animation := AnimationPane openWindow: 'Animation Examples'
Bouncer := AnimatedObject new
bouncer;
direction: 45;
speed: 1;
stepsPerFrame: 1;
frames: Pictures;
position: Animation extent // 2.
Animation addObject: Bouncer.
Bouncer animate
*************************
The 8th line of code used to read:
position: Animator pen extent // 2.
but it generated a walkback window which said "pen not understood". The
same thing happened for the Dog animation example following the bouncer
example.  I replaced "Animator" with "Animation" and removed the
reference to "pen" and it ran sucessfully multiple times.  The bouncer
turned out to be the wobbling ellipse from earlier in the tutorial.  The
dog animation also worked.  Then I cleared the frames by doing:
***************************
Bouncer frames do: [:each |
each release].
Chaser frames do: [:each |
   each release].
***************************
and followed that by doing
***************************
Animator := Chaser := Bouncer := nil      "get rid of the instance"
Animation := nil  "my addition, since Animator object did not seem
				to exist"
***************************
Then, I tried to run the animation again, executing the code above
(which should have created the new bouncer object and animated it) but
instead Smalltalk hung with 100 % CPU resources being consumed.

Why?  And how do I get animation working again?

Thanks
-- 
James Melhuish
Vensim Product Center, Ventana Systems, Inc.
82 Harvard Street, Newtonville MA 02160
home: 617-965-8859  email: jjms@world.std.com
