models: make a model-value generic.

diff --git a/basis/models/models.factor b/basis/models/models.factor
index a9de70bdcb99d3c3a36c618d44f5078e1ff90f6a..ed6e395f2982dd66df8a2788bbc59ab7dfe04f1f 100644 (file)
--- a/basis/models/models.factor
+++ b/basis/models/models.factor
@@ -53,8 +53,12 @@ DEFER: remove-connection
         drop
     ] if ;
 
+GENERIC: model-value ( model -- value )
+
+M: model model-value value>> ;
+
 : compute-model ( model -- value )
-    [ activate-model ] [ deactivate-model ] [ value>> ] tri ;
+    [ activate-model ] [ deactivate-model ] [ model-value ] tri ;
 
 GENERIC: model-changed ( model observer -- )
 M: object model-changed 2drop ;