Multimethods

2 files changed, 27 insertions, 24 deletions

diff --git a/src/boot.clj b/src/boot.clj
index 012e3a1d..20e7702f 100644
--- a/src/boot.clj
+++ b/src/boot.clj
@@ -296,14 +296,21 @@
   ([x form] `(. ~x ~form))
   ([x form & more] `(.. (. ~x ~form) ~@more)))
 
-;;polyfns
-(defmacro defpolyfn [name dispatch-fn]
-  `(def ~name (new clojure.lang.PolyFn ~dispatch-fn)))
+;;multimethods
+(defmacro defmulti
+  ([name dispatch-fn] (thisfn name dispatch-fn :default))
+  ([name dispatch-fn default-val]
+    `(def ~name (new clojure.lang.MultiFn ~dispatch-fn ~default-val))))
 
-(defmacro defmethod [polyfn dispatch-val & fn-tail]
-  `(let [pvar# (the-var ~polyfn)]
-     (locking pvar#
-        (. pvar# (bindRoot (.. pvar# (getRoot) (assoc ~dispatch-val (fn ~@fn-tail))))))))
+(defmacro defmethod [multifn dispatch-val & fn-tail]
+  `(let [pvar# (the-var ~multifn)]
+      (. pvar# (commuteRoot (fn [mf#] (. mf# (assoc ~dispatch-val (fn ~@fn-tail))))))))
+
+(defmacro remove-method [multifn dispatch-val]
+  `(let [pvar# (the-var ~multifn)]
+      (. pvar# (commuteRoot (fn [mf#] (. mf# (dissoc ~dispatch-val)))))))
+
+;;;;;;;;; var stuff      
 
 (defmacro binding [bindings & body]
   (let [var-ize (fn [var-vals]
@@ -600,7 +607,8 @@
 		peek pop nth contains get
 		assoc dissoc find keys vals merge
 		rseq sym name namespace locking ..
-		defpolyfn defmethod binding find-var
+		defmulti defmethod remove-method
+                binding find-var
 		ref deref deref! commute set sync
 		reduce reverse comp appl
 		every not-every any not-any
diff --git a/src/jvm/clojure/lang/MultiFn.java b/src/jvm/clojure/lang/MultiFn.java
index a122b199..53c0b8d5 100644
--- a/src/jvm/clojure/lang/MultiFn.java
+++ b/src/jvm/clojure/lang/MultiFn.java
@@ -14,48 +14,43 @@ package clojure.lang;
 
 public class MultiFn extends AFn{
 final public IFn dispatchFn;
-final public IFn defaultFn;
+final public Object defaultDispatchVal;
 final public IPersistentMap methodTable;
 
-public MultiFn(IFn dispatchFn, IFn defaultFn){
+public MultiFn(IFn dispatchFn, Object defaultDispatchVal){
 	this.dispatchFn = dispatchFn;
-	this.defaultFn = defaultFn;
+	this.defaultDispatchVal = defaultDispatchVal;
 	this.methodTable = PersistentHashMap.EMPTY;
 }
 
 public MultiFn assoc(Object dispatchVal, IFn method){
-	return new MultiFn(meta(), dispatchFn, defaultFn, methodTable.assoc(dispatchVal, method));
+	return new MultiFn(meta(), dispatchFn, defaultDispatchVal, methodTable.assoc(dispatchVal, method));
 }
 
-public MultiFn withDefaultFn(IFn newDefaultFn){
-	return new MultiFn(meta(), dispatchFn, newDefaultFn, methodTable);
-}
 
-public MultiFn without(Object dispatchVal){
-	return new MultiFn(meta(), dispatchFn,  defaultFn, methodTable.without(dispatchVal));
+public MultiFn dissoc(Object dispatchVal){
+	return new MultiFn(meta(), dispatchFn,  defaultDispatchVal, methodTable.without(dispatchVal));
 }
 
 public Obj withMeta(IPersistentMap meta){
 	if(meta == meta())
 		return this;
-	return new MultiFn(meta, dispatchFn, defaultFn, methodTable);
+	return new MultiFn(meta, dispatchFn, defaultDispatchVal, methodTable);
 }
 
-private MultiFn(IPersistentMap meta, IFn dispatchFn, IFn defaultFn, IPersistentMap dispatchTable){
+private MultiFn(IPersistentMap meta, IFn dispatchFn, Object defaultDispatchVal, IPersistentMap dispatchTable){
 	super(meta);
 	this.dispatchFn = dispatchFn;
-	this.defaultFn = defaultFn;
+	this.defaultDispatchVal = defaultDispatchVal;
 	this.methodTable = dispatchTable;
 }
 
 private IFn getFn(Object dispatchVal) throws Exception{
 	IFn targetFn = (IFn) methodTable.valAt(dispatchVal);
 	if(targetFn == null)
-		{
-		if(defaultFn != null)
-			return defaultFn;
+	    targetFn = (IFn) methodTable.valAt(defaultDispatchVal);
+	if(targetFn == null)
 		throw new IllegalArgumentException(String.format("No method for dispatch value: %s", dispatchVal));
-		}
 	return targetFn;
 }