[ltk-user] Stumper

[Thomas F. Burdick]

On 2/5/06, Kenny Tilton <ktilton at nyc.rr.com> wrote:
> This is one of my favorites ever:
>
>
> To do dataflow from Tk, I settled on:

Translating for Peter, this means Kenny is trying to make changes to
the Tk widgets (eg, a text box) show up as changes to c-input slots on
the Lisp side.  That way c-formulas can react to what the user typed.

>     trace add variable .w42 write "mytraceproc"
>
> And mytraceproc cloned from sendata et al.
>
> After a fascinating learning period I got it to work. Most of the time.
>
> When it fails (get this) it is because the sympol is in a different
> package (My "LTk2" package.) That is the listener package while I am
> running. Normally callback gets symbols in LTk, and that is how they are
> stored in the callback hash table.

The internal interface to callbacks is: create-name, add-callback,
remove-callback, and callback.  Contrary to what the lambda-list of
what the last three would make you believe, callbacks are named by
strings, not symbols.  You should get the name for a new callback from
create-name.  I'll be fixing that in subversion if Peter doesn't beat
me to it.