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))
,@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
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