[cells-devel] Re: [cells-gtk-devel] lots of circular cells in cells-gtk3?

[Ken Tilton]

Peter Hildebrandt wrote:
> As you saw in my other mail, I found the intermediate cause of the
> problem:  I had included a reference to (id self) in
> initialize-instance of widget.  For some reason that causes the
> circularity detection to raise its voice.
> 
> What I don't understand, however, is why a reference to the slot in
> initialize-instance :after brings out circularity.
> 
> For now, I moved the stuff into the rule for the id slot itself, so
> when the id is calculated, I use it right away, and don't have to
> worry about cell access.  slot-value would have been another option, I
> suppose.
> 
> But still:  why???

Recently some evil programming took forever to debug because I was 
re-entering a rule without realizing it. After figuring out that that 
was happening and fixing the cause of that, I looked to see why rule 
re-entrance had not been detected, which I seemed to recall it always 
had been.

Turns out the rule began with without-c-dependency as a trick to run 
only once. That macro simply:

     `(let ((cells::*call-stack* nil))
        , at body)

And that worked because the dependent cell was always identifed as (car 
cells::*call-stack*).

Well, I like early bug detection you may have noticed recently <g>, so I 
decided the macro without-c-dependency should leave the *call-stack* 
intact and instead bind a separate new *depender* special to nil, with 
*depender* being the, well, depender honored by the Cells machinery.

You should not have been doing cells-y stuff in i-i, but you got away 
with it because of the old without-c-dependency behavior, so...

...congratulations, you are the first victim to fall into my new bug 
trap. :)

kt