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Added some comments

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apatil committed May 17, 2009
1 parent e28053f commit 1a031c0bc22f966d458b794b8eee082b50261fe3
Showing with 9 additions and 9 deletions.
  1. +9 −9 selfless.clj
@@ -3,9 +3,6 @@
(set! *warn-on-reflection* true)
-; TODO: create-agent should add watchers to parents. That way you can remove some update code
-; TODO: and you don't have to rely on knowing who the children are when updating.
; TODO: Don't use the state monad in with-flow. You want to make the state explicit at all times.
; TODO: You don't need to worry about preferred errors at this level. ZeroProbabilities
; TODO: will always happen at leaf nodes, so the logp-accessor fn can deal with them.
@@ -93,6 +90,8 @@
(fn [cur-val parent]
(let [parent-val (deref parent)]
(if (::status parent-val)
+ ; If the parent is up-to-date or in error, remove it from the set of keys
+ ; that need updates.
[(assoc (cur-val 0) parent-key (::value parent-val)) (disj (cur-val 1) parent-key)]))))
(add-recording-watcher [[key val] collating-agent]
@@ -108,19 +107,19 @@
(watch-fn [parent-key child-node]
"This function is sent to the child when the parent's value changes
by a watcher."
- (let [parents (:parents child-node)
- update-fn (:fn child-node)]
+ (let [parents (:parents child-node) update-fn (:fn child-node)]
(fn [child-val parent]
- (let [parent-val (deref parent)
- status (::status parent-val)
- value (::value parent-val)]
+ (let [parent-val (deref parent) status (::status parent-val) value (::value parent-val)]
(= ::up-to-date status)
+ ; If the parent is now up-to-date, assoc its value.
(let [new-vals (assoc child-val parent-key value)]
(if (= (count new-vals) (count parents))
+ ; Compute if possible.
(try-update update-fn new-vals)
(= ::error status)
+ ; If the parent is now in error, replicate the error.
{::value value ::status ::error}
@@ -142,9 +141,10 @@
a (agent parent-vals)]
; Update the state with new agents at this node and at the parent nodes
[(assoc state key a)
- ; If this is a root node, add it to the roots.
(if (= (count parent-vals) (count parents))
+ ; If this is a root node, add it to the roots.
(conj roots key)
+ ; Otherwise, add watchers to its parents.
(map-now #(add-update-watcher % key a state) parents)

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