UI2 stepProcess infinite blowup and the dangers of not cloning

David Goehrig dave at nexttolast.com
Fri May 25 13:42:39 UTC 2012

So I was trying to shoot a screen cast last night of a web server project
in Self I wrote and after making some modifications to my image that
seemed innocuous I ended up with a blowup in UI2 stepProcess, in which
right clicking on basically any element triggers an "Error: first is

Error: first is absent.
Receiver is: a link.

Then if you click on Stack you get:

No 'isReflecteeBlockMethodActivation' slot found in a list.
No 'isReflecteeBlockMethodActivation' slot found in a list.
Error: first is absent.
Receiver is: a link.
UI step failed twice in Self 1(type: worldMorph) -- starting debugger in
new world

Restarting the image in another world, it comes down to something is
calling  hashElement: e on an empty list.

Well what was going on here?

So digging deeper I went in and looked at the list... oh wow

list rep is a link that is pointing to objects which is pointing to a
circular list produced by an old version of a typo that was in application!

How did that happen?

Well it looks like one of the methods had not been updated and called an
old object that was never scavenged that had a copy of the code that did
the wrong thing...

When I ran the web server it called that code, which wasn't in the objects
I had been editing..

So how to fix it?

Well list rep needs to point to a link that points to itself... done...

Wow right clicking on anything works again... woot!

I wish I had this entire thing on the screen grab, but I don't.  It would
have demonstrated how incredibly cool Self is where you can debug and alter
a live image in the image itself even when you shoot yourself in the foot.


-=-=-=-=-=-=-=-=-=-=- http://blog.dloh.org/
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