Let's not force validation on every Tom, Dick and Harry. This is a little

verbose, so maybe I'll change my mind again later and do something yet again
different.

src/java/com/samskivert/jdbc/depot/CacheInvalidator.java

@@ -27,16 +27,6 @@ package com.samskivert.jdbc.depot;
  */
 public interface CacheInvalidator
 {
-    /**
-     * Validates that this invalidator operates on the supplied persistent record class. This helps
-     * to catch programmer errors where one record type is used for a query clause and another is
-     * used for the cache invalidator.
-     *
-     * @exception IllegalArgumentException thrown if the supplied persistent record class does not
-     * match the class that this invalidator will flush from the cache.
-     */
-    public void validateFlushType (Class<?> pClass);
-
     /**
      * Must invalidate all cache entries that depend on the records being modified or deleted.
      * This method is called just before the database statement is executed.

src/java/com/samskivert/jdbc/depot/DepotRepository.java

@@ -392,8 +392,8 @@ public abstract class DepotRepository
         Class<T> type, final WhereClause key, CacheInvalidator invalidator, Object... fieldsValues)
         throws PersistenceException
     {
-        if (invalidator != null) {
-            invalidator.validateFlushType(type); // sanity check
+        if (invalidator instanceof ValidatingCacheInvalidator) {
+            ((ValidatingCacheInvalidator)invalidator).validateFlushType(type); // sanity check
         }
         key.validateQueryType(type); // and another
 
@@ -521,8 +521,8 @@ public abstract class DepotRepository
     {
         requireNotComputed(type, "updateLiteral");
 
-        if (invalidator != null) {
-            invalidator.validateFlushType(type); // sanity check
+        if (invalidator instanceof ValidatingCacheInvalidator) {
+            ((ValidatingCacheInvalidator)invalidator).validateFlushType(type); // sanity check
         }
         key.validateQueryType(type); // and another
 
@@ -667,8 +667,8 @@ public abstract class DepotRepository
         Class<T> type, final WhereClause key, CacheInvalidator invalidator)
         throws PersistenceException
     {
-        if (invalidator != null) {
-            invalidator.validateFlushType(type); // sanity check
+        if (invalidator instanceof ValidatingCacheInvalidator) {
+            ((ValidatingCacheInvalidator)invalidator).validateFlushType(type); // sanity check
         }
         key.validateQueryType(type); // and another
 

src/java/com/samskivert/jdbc/depot/Key.java

@@ -41,7 +41,7 @@ import com.samskivert.util.StringUtil;
  * a convenience, and may also be instantiated explicitly.
  */
 public class Key<T extends PersistentRecord> extends WhereClause
-    implements SQLExpression, CacheKey, CacheInvalidator, Serializable
+    implements SQLExpression, CacheKey, ValidatingCacheInvalidator, Serializable
 {
     /** An expression that contains our key columns and values. */
     public static class WhereCondition<U extends PersistentRecord> implements SQLExpression
@@ -188,7 +188,7 @@ public class Key<T extends PersistentRecord> extends WhereClause
         return this; // TODO: Optimally return a special class here containing only _values.
     }
 
-    // from CacheInvalidator
+    // from ValidatingCacheInvalidator
     public void validateFlushType (Class<?> pClass)
     {
         if (!pClass.equals(condition.getPersistentClass())) {

src/java/com/samskivert/jdbc/depot/MultiKey.java

@@ -33,7 +33,7 @@ import com.samskivert.jdbc.depot.expression.ExpressionVisitor;
  * it can be sent into e.g. {@link DepotRepository#deleteAll) and have it clean up after itself.
  */
 public class MultiKey<T extends PersistentRecord> extends WhereClause
-    implements CacheInvalidator
+    implements ValidatingCacheInvalidator
 {
     /**
      * Constructs a new single-column {@code MultiKey} with the given value range.
@@ -112,7 +112,7 @@ public class MultiKey<T extends PersistentRecord> extends WhereClause
         // nothing to add
     }
 
-    // from CacheInvalidator
+    // from ValidatingCacheInvalidator
     public void validateFlushType (Class<?> pClass)
     {
         if (!pClass.equals(_pClass)) {

src/java/com/samskivert/jdbc/depot/ValidatingCacheInvalidator.java

@@ -0,0 +1,38 @@
+//
+// $Id$
+//
+// samskivert library - useful routines for java programs
+// Copyright (C) 2001-2007 Michael Bayne
+// 
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.samskivert.jdbc.depot;
+
+/**
+ * An augmented cache invalidator interface for invalidators that can ensure that they are
+ * operating on the proper persistent record class.
+ */
+public interface ValidatingCacheInvalidator extends CacheInvalidator
+{
+    /**
+     * Validates that this invalidator operates on the supplied persistent record class. This helps
+     * to catch programmer errors where one record type is used for a query clause and another is
+     * used for the cache invalidator.
+     *
+     * @exception IllegalArgumentException thrown if the supplied persistent record class does not
+     * match the class that this invalidator will flush from the cache.
+     */
+    public void validateFlushType (Class<?> pClass);
+}