Ken Tilton wrote:
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*).
In case that last bit is not clear, what I meant was "That worked [to
avoid dependency] because the dependent cell was identified by taking
the car of the *call-stack*"
btw, note that this undetected re-entrance would happen if /any/ rule in
the chain leading back to the same cell did a without-c-dependency.
kt
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