Set the KeypathObserver on the Rivets object. Add missing source documentation.

@@ -12,6 +12,7 @@ class Rivets.Binding
     @setBinder()
     @setObserver()
 
+  # Sets the binder to use when binding and syncing.
   setBinder: =>
     unless @binder = @view.binders[@type]
       for identifier, value of @view.binders
@@ -25,8 +26,10 @@ class Rivets.Binding
     @binder or= @view.binders['*']
     @binder = {routine: @binder} if @binder instanceof Function
 
+  # Sets a keypath observer that will notify this binding when any intermediary
+  # keys are changed.
   setObserver: =>
-    @observer = new KeypathObserver @view, @view.models, @keypath, (obs) =>
+    @observer = new Rivets.KeypathObserver @view, @view.models, @keypath, (obs) =>
       @unbind true if @key
       @model = obs.target
       @bind true if @key
@@ -95,7 +98,7 @@ class Rivets.Binding
 
     if @options.dependencies?.length
       for dependency in @options.dependencies
-        observer = new KeypathObserver @view, @model, dependency, (obs, prev) =>
+        observer = new Rivets.KeypathObserver @view, @model, dependency, (obs, prev) =>
           key = obs.key
           @view.adapters[key.interface].unsubscribe prev, key.path, @sync
           @view.adapters[key.interface].subscribe obs.target, key.path, @sync

-class KeypathObserver
+# Rivets.KeypathObserver
+# ----------------------
+
+# Parses and observes a full keypath with the appropriate adapters. Also
+# intelligently re-realizes the keypath when intermediary keys change.
+class Rivets.KeypathObserver
+  # Performs the initial parse, variable instantiation and keypath realization.
   constructor: (@view, @model, @keypath, @callback) ->
     @parse()
     @objectPath = []
     @target = @realize()
 
+  # Parses the keypath using the interfaces defined on the view. Sets variables
+  # for the tokenized keypath, as well as the end key.
   parse: =>
     interfaces = (k for k, v of @view.adapters)
 
@@ -17,12 +25,15 @@ class KeypathObserver
     @tokens = Rivets.KeypathParser.parse path, interfaces, root
     @key = @tokens.pop()
 
+  # Updates the keypath. This is called when any intermediate key is changed.
   update: =>
     unless (next = @realize()) is @target
       prev = @target
       @target = next
       @callback @, prev
 
+  # Realizes the full keypath, attaching observers for every key and correcting
+  # old observers to any changed objects in the keypath.
   realize: =>
     current = @model
 
@@ -40,6 +51,7 @@ class KeypathObserver
 
     current
 
+  # Unobserves any current observers set up on the keys.
   unobserve: =>
     for token, index in @tokens
       if obj = @objectPath[index]