Modifications to clone() on insertion and extraction from cache, from Zell. A

whole bunch of type safety jockeying and concretification of QueryClause by
yours truly.

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

@@ -65,7 +65,7 @@ public abstract class ConstructedQuery<T>
      *
      * This method is called by individual clauses.
      */
-    public String getTableAbbreviation (Class cl)
+    public String getTableAbbreviation (Class<? extends PersistentRecord> cl)
     {
         int ix = _classList.indexOf(cl);
         if (ix < 0) {
@@ -197,11 +197,13 @@ public abstract class ConstructedQuery<T>
      * class, as dictated by the key and query clauses.  A persistence context is supplied for
      * instantiation of marshallers, which may trigger table creations and schema migrations.
      */
-    protected ConstructedQuery (PersistenceContext ctx, Class type, QueryClause... clauses)
+    protected ConstructedQuery (PersistenceContext ctx, Class<? extends PersistentRecord> type,
+                                QueryClause... clauses)
         throws PersistenceException
     {
         _mainType = type;
-        Set<Class> classSet = new HashSet<Class>();
+        Set<Class<? extends PersistentRecord>> classSet =
+            new HashSet<Class<? extends PersistentRecord>>();
         if (type != null) {
             classSet.add(type);
         }
@@ -261,17 +263,17 @@ public abstract class ConstructedQuery<T>
         }
         _classMap = new HashMap<Class, DepotMarshaller>();
 
-        for (Class<?> c : classSet) {
+        for (Class<? extends PersistentRecord> c : classSet) {
             _classMap.put(c, ctx.getMarshaller(c));
         }
-        _classList = new ArrayList<Class>(classSet);
+        _classList = new ArrayList<Class<? extends PersistentRecord>>(classSet);
     }
     
     /** The persistent class to instantiate for the results. */
-    protected Class _mainType;
+    protected Class<? extends PersistentRecord> _mainType;
 
     /** A list of referenced classes, used to generate table abbreviations. */
-    protected List<Class> _classList;
+    protected List<Class<? extends PersistentRecord>> _classList;
 
     /** Classes mapped to marshallers, used for table names and field lists. */
     protected Map<Class, DepotMarshaller> _classMap;

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

@@ -63,7 +63,7 @@ import static com.samskivert.jdbc.depot.Log.log;
  * Handles the marshalling and unmarshalling of persistent instances to JDBC primitives ({@link
  * PreparedStatement} and {@link ResultSet}).
  */
-public class DepotMarshaller<T>
+public class DepotMarshaller<T extends PersistentRecord>
 {
     /** The name of a private static field that must be defined for all persistent object classes.
      * It is used to handle schema migration. If automatic schema migration is not desired, define

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

@@ -29,9 +29,6 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Map;
 
-import net.sf.ehcache.Cache;
-import net.sf.ehcache.Element;
-
 import com.samskivert.io.PersistenceException;
 import com.samskivert.jdbc.ConnectionProvider;
 import com.samskivert.jdbc.JDBCUtil;
@@ -66,7 +63,8 @@ public class DepotRepository
     /**
      * Loads the persistent object that matches the specified primary key.
      */
-    protected <T> T load (Class<T> type, Comparable primaryKey, QueryClause... clauses)
+    protected <T extends PersistentRecord> T load (Class<T> type, Comparable primaryKey,
+                                                   QueryClause... clauses)
         throws PersistenceException
     {
         clauses = ArrayUtil.append(clauses, _ctx.getMarshaller(type).makePrimaryKey(primaryKey));
@@ -76,7 +74,8 @@ public class DepotRepository
     /**
      * Loads the persistent object that matches the specified primary key.
      */
-    protected <T> T load (Class<T> type, String ix, Comparable val, QueryClause... clauses)
+    protected <T extends PersistentRecord> T load (Class<T> type, String ix, Comparable val,
+                                                   QueryClause... clauses)
         throws PersistenceException
     {
         clauses = ArrayUtil.append(clauses, new Key<T>(type, ix, val));
@@ -86,8 +85,9 @@ public class DepotRepository
     /**
      * Loads the persistent object that matches the specified two-column primary key.
      */
-    protected <T> T load (Class<T> type, String ix1, Comparable val1, String ix2,
+    protected <T extends PersistentRecord> T load (Class<T> type, String ix1, Comparable val1,
-                          Comparable val2, QueryClause... clauses)
+                                                   String ix2, Comparable val2,
+                                                   QueryClause... clauses)
         throws PersistenceException
     {
         clauses = ArrayUtil.append(clauses, new Key<T>(type, ix1, val1, ix2, val2));
@@ -97,8 +97,9 @@ public class DepotRepository
     /**
      * Loads the persistent object that matches the specified three-column primary key.
      */
-    protected <T> T load (Class<T> type, String ix1, Comparable val1, String ix2,
+    protected <T extends PersistentRecord> T load (Class<T> type, String ix1, Comparable val1,
-                          Comparable val2, String ix3, Comparable val3, QueryClause... clauses)
+                                                   String ix2, Comparable val2, String ix3,
+                                                   Comparable val3, QueryClause... clauses)
         throws PersistenceException
     {
         clauses = ArrayUtil.append(clauses, new Key<T>(type, ix1, val1, ix2, val2, ix3, val3));
@@ -108,7 +109,7 @@ public class DepotRepository
     /**
      * Loads the first persistent object that matches the supplied key.
      */
-    protected <T> T load (Class<T> type, QueryClause... clauses)
+    protected <T extends PersistentRecord> T load (Class<T> type, QueryClause... clauses)
         throws PersistenceException
     {
         final DepotMarshaller<T> marsh = _ctx.getMarshaller(type);
@@ -130,6 +131,7 @@ public class DepotRepository
                 }
             }
 
+            // from Query
             public void updateCache (PersistenceContext ctx, T result) {
                 CacheKey key = getCacheKey();
                 if (key == null) {
@@ -140,7 +142,18 @@ public class DepotRepository
                     // if we can, create a key from what was actually returned
                     key = marsh.getPrimaryKey(result);
                 }
-                ctx.cacheStore(key, result);
+                ctx.cacheStore(key, result != null ? result.clone() : null);
+            }
+
+            // from Query
+            public T transformCacheHit (CacheKey key, T value)
+            {
+                // we do not want to return a reference to the actual cached entity
+                if (value == null) {
+                    return null;
+                }
+                @SuppressWarnings("unchecked") T cvalue = (T) value.clone();
+                return cvalue;
             }
         });
     }
@@ -148,7 +161,7 @@ public class DepotRepository
     /**
      * Loads all persistent objects that match the specified key.
      */
-    protected <T,C extends Collection<T>> Collection<T> findAll (
+    protected <T extends PersistentRecord, C extends Collection<T>> Collection<T> findAll (
         Class<T> type, QueryClause... clauses)
         throws PersistenceException
     {
@@ -169,13 +182,33 @@ public class DepotRepository
                 }
             }
 
+            // from Query
             public void updateCache (PersistenceContext ctx, ArrayList<T> result) {
                 if (marsh.hasPrimaryKey()) {
                     for (T bit : result) {
-                        ctx.cacheStore(marsh.getPrimaryKey(bit), bit);
+                        ctx.cacheStore(marsh.getPrimaryKey(bit), bit.clone());
                     }
                 }
             }
+
+            // from Query
+            public ArrayList<T> transformCacheHit (CacheKey key, ArrayList<T> bits)
+            {
+                if (bits == null) {
+                    return bits;
+                }
+
+                ArrayList<T> result = new ArrayList<T>();
+                for (T bit : bits) {
+                    if (bit != null) {
+                        @SuppressWarnings("unchecked") T cbit = (T) bit.clone();
+                        result.add(cbit);
+                    } else {
+                        result.add(null);
+                    }
+                }
+                return result;
+            }
         });
     }
 
@@ -185,7 +218,7 @@ public class DepotRepository
      *
      * @return the number of rows modified by this action, this should always be one.
      */
-    protected <T> int insert (final T record)
+    protected <T extends PersistentRecord> int insert (T record)
         throws PersistenceException
     {
         final DepotMarshaller marsh = _ctx.getMarshaller(record.getClass());
@@ -194,12 +227,12 @@ public class DepotRepository
         return _ctx.invoke(new CachingModifier<T>(record, key, key) {
             public int invoke (Connection conn) throws SQLException {
                 // update our modifier's key so that it can cache our results
-                updateKey(marsh.assignPrimaryKey(conn, record, false));
+                updateKey(marsh.assignPrimaryKey(conn, _result, false));
-                PreparedStatement stmt = marsh.createInsert(conn, record);
+                PreparedStatement stmt = marsh.createInsert(conn, _result);
                 try {
                     int mods = stmt.executeUpdate();
                     // check again in case we have a post-factum key generator
-                    updateKey(marsh.assignPrimaryKey(conn, record, true));
+                    updateKey(marsh.assignPrimaryKey(conn, _result, true));
                     return mods;
                 } finally {
                     JDBCUtil.close(stmt);
@@ -214,7 +247,7 @@ public class DepotRepository
      *
      * @return the number of rows modified by this action.
      */
-    protected <T> int update (final T record)
+    protected <T extends PersistentRecord> int update (T record)
         throws PersistenceException
     {
         final DepotMarshaller marsh = _ctx.getMarshaller(record.getClass());
@@ -224,7 +257,7 @@ public class DepotRepository
         }
         return _ctx.invoke(new CachingModifier<T>(record, key, key) {
             public int invoke (Connection conn) throws SQLException {
-                PreparedStatement stmt = marsh.createUpdate(conn, record, key);
+                PreparedStatement stmt = marsh.createUpdate(conn, _result, key);
                 try {
                     return stmt.executeUpdate();
                 } finally {
@@ -240,7 +273,7 @@ public class DepotRepository
      *
      * @return the number of rows modified by this action.
      */
-    protected <T> int update (final T record, final String... modifiedFields)
+    protected <T extends PersistentRecord> int update (T record, final String... modifiedFields)
         throws PersistenceException
     {
         final DepotMarshaller marsh = _ctx.getMarshaller(record.getClass());
@@ -250,7 +283,7 @@ public class DepotRepository
         }
         return _ctx.invoke(new CachingModifier<T>(record, key, key) {
             public int invoke (Connection conn) throws SQLException {
-                PreparedStatement stmt = marsh.createUpdate(conn, record, key, modifiedFields);
+                PreparedStatement stmt = marsh.createUpdate(conn, _result, key, modifiedFields);
                 try {
                     return stmt.executeUpdate();
                 } finally {
@@ -270,8 +303,8 @@ public class DepotRepository
      *
      * @return the number of rows modified by this action.
      */
-    protected <T> int updatePartial (Class<T> type, Comparable primaryKey,
+    protected <T extends PersistentRecord> int updatePartial (
-                                     Map<String,Object> updates)
+        Class<T> type, Comparable primaryKey, Map<String,Object> updates)
         throws PersistenceException
     {
         Object[] fieldsValues = new Object[updates.size()*2];
@@ -293,7 +326,8 @@ public class DepotRepository
      *
      * @return the number of rows modified by this action.
      */
-    protected <T> int updatePartial (Class<T> type, Comparable primaryKey, Object... fieldsValues)
+    protected <T extends PersistentRecord> int updatePartial (
+        Class<T> type, Comparable primaryKey, Object... fieldsValues)
         throws PersistenceException
     {
         Key<T> key = _ctx.getMarshaller(type).makePrimaryKey(primaryKey);
@@ -312,8 +346,8 @@ public class DepotRepository
      *
      * @return the number of rows modified by this action.
      */
-    protected <T> int updatePartial (Class<T> type, final Where key, CacheInvalidator invalidator,
+    protected <T extends PersistentRecord> int updatePartial (
-                                     Object... fieldsValues)
+        Class<T> type, final Where key, CacheInvalidator invalidator, Object... fieldsValues)
         throws PersistenceException
     {
         // separate the arguments into keys and values
@@ -354,7 +388,8 @@ public class DepotRepository
      *
      * @return the number of rows modified by this action.
      */
-    protected <T> int updateLiteral (Class<T> type, Comparable primaryKey, String... fieldsValues)
+    protected <T extends PersistentRecord> int updateLiteral (
+        Class<T> type, Comparable primaryKey, String... fieldsValues)
         throws PersistenceException
     {
         Key<T> key = _ctx.getMarshaller(type).makePrimaryKey(primaryKey);
@@ -378,8 +413,8 @@ public class DepotRepository
      *
      * @return the number of rows modified by this action.
      */
-    protected <T> int updateLiteral (Class<T> type, final Where key, CacheInvalidator invalidator,
+    protected <T extends PersistentRecord> int updateLiteral (
-                                     String... fieldsValues)
+        Class<T> type, final Where key, CacheInvalidator invalidator, String... fieldsValues)
         throws PersistenceException
     {
         // separate the arguments into keys and values
@@ -410,7 +445,7 @@ public class DepotRepository
      *
      * @return the number of rows modified by this action, this should always be one.
      */
-    protected <T> int store (final T record)
+    protected <T extends PersistentRecord> int store (T record)
         throws PersistenceException
     {
         final DepotMarshaller marsh = _ctx.getMarshaller(record.getClass());
@@ -422,7 +457,7 @@ public class DepotRepository
                     // if our primary key isn't null, update rather than insert the record
                     // before been persisted and insert
                     if (key != null) {
-                        stmt = marsh.createUpdate(conn, record, key);
+                        stmt = marsh.createUpdate(conn, _result, key);
                         int mods = stmt.executeUpdate();
                         if (mods > 0) {
                             return mods;
@@ -432,10 +467,10 @@ public class DepotRepository
 
                     // if the update modified zero rows or the primary key was obviously unset, do
                     // an insertion
-                    updateKey(marsh.assignPrimaryKey(conn, record, false));
+                    updateKey(marsh.assignPrimaryKey(conn, _result, false));
-                    stmt = marsh.createInsert(conn, record);
+                    stmt = marsh.createInsert(conn, _result);
                     int mods = stmt.executeUpdate();
-                    updateKey(marsh.assignPrimaryKey(conn, record, true));
+                    updateKey(marsh.assignPrimaryKey(conn, _result, true));
                     return mods;
 
                 } finally {
@@ -451,7 +486,7 @@ public class DepotRepository
      *
      * @return the number of rows deleted by this action.
      */
-    protected <T> int delete (T record)
+    protected <T extends PersistentRecord> int delete (T record)
         throws PersistenceException
     {
         @SuppressWarnings("unchecked") Class<T> type = (Class<T>)record.getClass();
@@ -468,7 +503,7 @@ public class DepotRepository
      *
      * @return the number of rows deleted by this action.
      */
-    protected <T> int delete (Class<T> type, Comparable primaryKeyValue)
+    protected <T extends PersistentRecord> int delete (Class<T> type, Comparable primaryKeyValue)
         throws PersistenceException
     {
         Key<T> primaryKey = _ctx.getMarshaller(type).makePrimaryKey(primaryKeyValue);
@@ -480,7 +515,8 @@ public class DepotRepository
      *
      * @return the number of rows deleted by this action.
      */
-    protected <T> int deleteAll (Class<T> type, final Where key, CacheInvalidator invalidator)
+    protected <T extends PersistentRecord> int deleteAll (
+        Class<T> type, final Where key, CacheInvalidator invalidator)
         throws PersistenceException
     {
         final DepotMarshaller marsh = _ctx.getMarshaller(type);

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

@@ -23,9 +23,9 @@ package com.samskivert.jdbc.depot;
 import java.io.Serializable;
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
-import java.util.Arrays;
+import java.util.ArrayList;
+import java.util.Collection;
 import java.util.HashMap;
-import java.util.List;
 import java.util.Map;
 
 import com.samskivert.jdbc.depot.clause.Where;
@@ -37,7 +37,7 @@ import com.samskivert.jdbc.depot.clause.Where;
  * itself upon modification. This class is created by many {@link DepotMarshaller} methods as
  * a convenience, and may also be instantiated explicitly.
  */
-public class Key<T> extends Where
+public class Key<T extends PersistentRecord> extends Where
     implements CacheKey, CacheInvalidator
 {
     /**
@@ -94,13 +94,16 @@ public class Key<T> extends Where
     }
 
     // from QueryClause
-    public List<Class> getClassSet()
+    public Collection<Class<? extends PersistentRecord>> getClassSet ()
     {
-        return Arrays.asList(new Class[] { _pClass });
+        ArrayList<Class<? extends PersistentRecord>> set =
+            new ArrayList<Class<? extends PersistentRecord>>();
+        set.add(_pClass);
+        return set;
     }
 
     // from QueryClause
-    public void appendClause (ConstructedQuery query, StringBuilder builder)
+    public void appendClause (ConstructedQuery<?> query, StringBuilder builder)
     {
         builder.append(" where ");
         boolean first = true;

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

@@ -59,7 +59,7 @@ public abstract class Modifier
      * presuming both _key and _result are non-null. These variables may be set or modified
      * during execution in addition to being supplied to the constructor.
      */
-    public static abstract class CachingModifier<T> extends Modifier
+    public static abstract class CachingModifier<T extends PersistentRecord> extends Modifier
     {
         /**
          * Construct a new CachingModifier with the given result, cache key, and invalidator,
@@ -89,7 +89,7 @@ public abstract class Modifier
             super.cacheUpdate(ctx);
             // if we have both a key and a record, cache
             if (_key != null && _result != null) {
-                ctx.cacheStore(_key, _result);
+                ctx.cacheStore(_key, _result.clone());
             }
         }
 

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

@@ -22,9 +22,9 @@ package com.samskivert.jdbc.depot;
 
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
-import java.util.Arrays;
+import java.util.ArrayList;
+import java.util.Collection;
 import java.util.HashMap;
-import java.util.List;
 import java.util.Map;
 
 import com.samskivert.jdbc.depot.clause.Where;
@@ -34,7 +34,7 @@ import com.samskivert.jdbc.depot.clause.Where;
  * does not implement {@link CacheKey} but it does implement {@link CacheInvalidator} which means
  * it can be sent into e.g. {@link DepotRepository#deleteAll) and have it clean up after itself.
  */
-public class MultiKey<T> extends Where
+public class MultiKey<T extends PersistentRecord> extends Where
     implements CacheInvalidator
 {
     /**
@@ -85,13 +85,16 @@ public class MultiKey<T> extends Where
     }
 
     // from QueryClause
-    public List<Class> getClassSet()
+    public Collection<Class<? extends PersistentRecord>> getClassSet ()
     {
-        return Arrays.asList(new Class[] { _pClass });
+        ArrayList<Class<? extends PersistentRecord>> set =
+            new ArrayList<Class<? extends PersistentRecord>>();
+        set.add(_pClass);
+        return set;
     }
 
     // from QueryClause
-    public void appendClause (ConstructedQuery query, StringBuilder builder)
+    public void appendClause (ConstructedQuery<?> query, StringBuilder builder)
     {
         builder.append(" where ");
         boolean first = true;

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

@@ -140,7 +140,7 @@ public class PersistenceContext
      * and register a pre-migration for every single schema migration and they will then be
      * guaranteed to be run in registration order and with predictable pre- and post-conditions.
      */
-    public <T> void registerMigration (Class<T> type, EntityMigration migration)
+    public <T extends PersistentRecord> void registerMigration (Class<T> type, EntityMigration migration)
     {
         getRawMarshaller(type).registerMigration(migration);
     }
@@ -149,7 +149,7 @@ public class PersistenceContext
      * Returns the marshaller for the specified persistent object class, creating and initializing
      * it if necessary.
      */
-    public <T> DepotMarshaller<T> getMarshaller (Class<T> type)
+    public <T extends PersistentRecord> DepotMarshaller<T> getMarshaller (Class<T> type)
         throws PersistenceException
     {
         DepotMarshaller<T> marshaller = getRawMarshaller(type);
@@ -176,7 +176,11 @@ public class PersistenceContext
                 if (cacheHit != null) {
                     Log.debug("invoke: cache hit [hit=" + cacheHit + "]");
                     @SuppressWarnings("unchecked") T value = (T) cacheHit.getValue();
-                    return value;
+                    value = query.transformCacheHit(key, value);
+                    if (value != null) {
+                        return value;
+                    }
+                    Log.debug("invoke: transformCacheHit returned null; rejecting cached value.");
                 }
             }
             Log.debug("invoke: cache miss [key=" + key + "]");
@@ -337,7 +341,7 @@ public class PersistenceContext
      * Looks up and creates, but does not initialize, the marshaller for the specified Entity
      * type.
      */
-    protected <T> DepotMarshaller<T> getRawMarshaller (Class<T> type)
+    protected <T extends PersistentRecord> DepotMarshaller<T> getRawMarshaller (Class<T> type)
     {
         @SuppressWarnings("unchecked") DepotMarshaller<T> marshaller =
             (DepotMarshaller<T>)_marshallers.get(type);

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

@@ -0,0 +1,41 @@
+//
+// $Id$
+//
+// samskivert library - useful routines for java programs
+// Copyright (C) 2007 Michael Bayne, Pär Winzell
+// 
+// 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;
+
+import java.io.Serializable;
+
+/**
+ * The base class for all persistent records used in Depot. Persistent records must be cloneable
+ * and serializable; this class is used to enforce those requirements.
+ */
+public class PersistentRecord
+    implements Cloneable, Serializable
+{
+    @Override // from Object
+    public PersistentRecord clone ()
+    {
+        try {
+            return (PersistentRecord) super.clone();
+        } catch (CloneNotSupportedException cnse) {
+            throw new RuntimeException(cnse); // this should never happen
+        }
+    }
+}

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

@@ -38,9 +38,15 @@ public interface Query<T>
      */
     public T invoke (Connection conn)
         throws SQLException;
-    
+
+    /**
+     * Overriden by subclasses to perform special operations when the query would return a cache
+     * hit. The value may be mutated, modified, or null may be return to force a database hit.
+     */
+    public T transformCacheHit (CacheKey key, T value);
+
     /**
      * Overriden by subclasses to perform case-by-case cache updates.
      */
-    void updateCache (PersistenceContext ctx, T result);
+    public void updateCache (PersistenceContext ctx, T result);
 }

src/java/com/samskivert/jdbc/depot/clause/FieldOverride.java

@@ -20,12 +20,9 @@
 
 package com.samskivert.jdbc.depot.clause;
 
-import java.sql.PreparedStatement;
-import java.sql.SQLException;
-import java.util.Collection;
-
 import com.samskivert.io.PersistenceException;
 import com.samskivert.jdbc.depot.ConstructedQuery;
+import com.samskivert.jdbc.depot.PersistentRecord;
 import com.samskivert.jdbc.depot.expression.ColumnExp;
 import com.samskivert.jdbc.depot.expression.LiteralExp;
 import com.samskivert.jdbc.depot.expression.SQLExpression;
@@ -38,8 +35,7 @@ import com.samskivert.jdbc.depot.expression.SQLExpression;
  * table through a {@link ColumnExp}, or a literal expression such as COUNT(*) through a
  * {@link LiteralExp}.
  */
-public class FieldOverride
+public class FieldOverride extends QueryClause
-    implements QueryClause
 {
     public FieldOverride (String field, String str)
         throws PersistenceException
@@ -47,7 +43,7 @@ public class FieldOverride
         this(field, new LiteralExp(str));
     }
 
-    public FieldOverride (String field, Class pClass, String pCol)
+    public FieldOverride (String field, Class<? extends PersistentRecord> pClass, String pCol)
         throws PersistenceException
     {
         this(field, new ColumnExp(pClass, pCol));
@@ -69,25 +65,12 @@ public class FieldOverride
     }
 
     // from QueryClause
-    public Collection<Class> getClassSet ()
+    public void appendClause (ConstructedQuery<?> query, StringBuilder builder)
-    {
-        return null;
-    }
-
-    // from QueryClause
-    public void appendClause (ConstructedQuery query, StringBuilder builder)
     {
         _override.appendExpression(query, builder);
         builder.append(" as ").append(_field);
     }
 
-    // from QueryClause
-    public int bindArguments (PreparedStatement pstmt, int argIdx)
-        throws SQLException
-    {
-        return argIdx;
-    }
-
     /** The name of the field on the persistent object to override. */
     protected String _field;
 

src/java/com/samskivert/jdbc/depot/clause/ForUpdate.java

@@ -20,34 +20,16 @@
 
 package com.samskivert.jdbc.depot.clause;
 
-import java.sql.PreparedStatement;
-import java.sql.SQLException;
-import java.util.Collection;
-
 import com.samskivert.jdbc.depot.ConstructedQuery;
 
 /**
  *  Represents a FOR UPDATE clause.
  */
-public class ForUpdate
+public class ForUpdate extends QueryClause
-    implements QueryClause
 {
     // from QueryClause
-    public Collection<Class> getClassSet ()
+    public void appendClause (ConstructedQuery<?> query, StringBuilder builder)
-    {
-        return null;
-    }
-
-    // from QueryClause
-    public void appendClause (ConstructedQuery query, StringBuilder builder)
     {
         builder.append(" for update ");
     }
-
-    // from QueryClause
-    public int bindArguments (PreparedStatement pstmt, int argIdx)
-        throws SQLException
-    {
-        return argIdx;
-    }
 }

src/java/com/samskivert/jdbc/depot/clause/FromOverride.java

@@ -20,53 +20,45 @@
 
 package com.samskivert.jdbc.depot.clause;
 
-import java.sql.PreparedStatement;
+import java.util.ArrayList;
-import java.sql.SQLException;
-import java.util.Arrays;
 import java.util.Collection;
 
 import com.samskivert.io.PersistenceException;
 import com.samskivert.jdbc.depot.ConstructedQuery;
+import com.samskivert.jdbc.depot.PersistentRecord;
+import com.samskivert.util.CollectionUtil;
 
 /**
  *  Completely overrides the FROM clause, if it exists.
  */
-public class FromOverride
+public class FromOverride extends QueryClause
-    implements QueryClause
 {
-    public FromOverride (Class... fromClasses)
+    public FromOverride (Class<? extends PersistentRecord>... fromClasses)
         throws PersistenceException
     {
-        _fromClasses = fromClasses;
+        CollectionUtil.addAll(_fromClasses, fromClasses);
     }
 
     // from QueryClause
-    public Collection<Class> getClassSet ()
+    public Collection<Class<? extends PersistentRecord>> getClassSet ()
     {
-        return Arrays.asList(_fromClasses);
+        return _fromClasses;
     }
 
     // from QueryClause
-    public void appendClause (ConstructedQuery query, StringBuilder builder)
+    public void appendClause (ConstructedQuery<?> query, StringBuilder builder)
     {
         builder.append(" from " );
-        for (int ii = 0; ii < _fromClasses.length; ii++) {
+        for (int ii = 0; ii < _fromClasses.size(); ii++) {
             if (ii > 0) {
                 builder.append(", ");
             }
-            builder.append(query.getTableName(_fromClasses[ii])).
+            builder.append(query.getTableName(_fromClasses.get(ii))).
-                append(" as ").
+                append(" as ").append(query.getTableAbbreviation(_fromClasses.get(ii)));
-                append(query.getTableAbbreviation(_fromClasses[ii]));
         }
     }
 
-    // from QueryClause
-    public int bindArguments (PreparedStatement pstmt, int argIdx)
-        throws SQLException
-    {
-        return argIdx;
-    }
-
     /** The classes of the tables we're selecting from. */
-    protected Class[] _fromClasses;
+    protected ArrayList<Class<? extends PersistentRecord>> _fromClasses =
+        new ArrayList<Class<? extends PersistentRecord>>();
 }

src/java/com/samskivert/jdbc/depot/clause/GroupBy.java

@@ -22,7 +22,6 @@ package com.samskivert.jdbc.depot.clause;
 
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
-import java.util.Collection;
 
 import com.samskivert.jdbc.depot.ConstructedQuery;
 import com.samskivert.jdbc.depot.expression.SQLExpression;
@@ -30,8 +29,7 @@ import com.samskivert.jdbc.depot.expression.SQLExpression;
 /**
  *  Represents a GROUP BY clause.
  */
-public class GroupBy
+public class GroupBy extends QueryClause
-    implements QueryClause
 {
     public GroupBy (SQLExpression... values)
     {
@@ -39,13 +37,7 @@ public class GroupBy
     }
 
     // from QueryClause
-    public Collection<Class> getClassSet ()
+    public void appendClause (ConstructedQuery<?> query, StringBuilder builder)
-    {
-        return null;
-    }
-
-    // from QueryClause
-    public void appendClause (ConstructedQuery query, StringBuilder builder)
     {
         builder.append(" group by ");
         for (int ii = 0; ii < _values.length; ii++) {

src/java/com/samskivert/jdbc/depot/clause/Join.java

@@ -22,22 +22,23 @@ package com.samskivert.jdbc.depot.clause;
 
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
-import java.util.Arrays;
+import java.util.ArrayList;
 import java.util.Collection;
 
 import com.samskivert.io.PersistenceException;
 import com.samskivert.jdbc.depot.ConstructedQuery;
+import com.samskivert.jdbc.depot.PersistentRecord;
 import com.samskivert.jdbc.depot.expression.ColumnExp;
-import com.samskivert.jdbc.depot.operator.SQLOperator;
 import com.samskivert.jdbc.depot.operator.Conditionals.*;
+import com.samskivert.jdbc.depot.operator.SQLOperator;
 
 /**
  *  Represents a JOIN -- currently just an INNER one.
  */
-public class Join
+public class Join extends QueryClause
-    implements QueryClause
 {
-    public Join (Class pClass, String pCol, Class joinClass, String jCol)
+    public Join (Class<? extends PersistentRecord> pClass, String pCol,
+                 Class<? extends PersistentRecord> joinClass, String jCol)
         throws PersistenceException
     {
         _joinClass = joinClass;
@@ -51,20 +52,23 @@ public class Join
         _joinCondition = new Equals(primary, join);
     }
 
-    public Join (Class joinClass, SQLOperator joinCondition)
+    public Join (Class<? extends PersistentRecord> joinClass, SQLOperator joinCondition)
     {
         _joinClass = joinClass;
         _joinCondition = joinCondition;
     }
 
     // from QueryClause
-    public Collection<Class> getClassSet ()
+    public Collection<Class<? extends PersistentRecord>> getClassSet ()
     {
-        return Arrays.asList(new Class[] { _joinClass });
+        ArrayList<Class<? extends PersistentRecord>> set =
+            new ArrayList<Class<? extends PersistentRecord>>();
+        set.add(_joinClass);
+        return set;
     }
 
     // from QueryClause
-    public void appendClause (ConstructedQuery query, StringBuilder builder)
+    public void appendClause (ConstructedQuery<?> query, StringBuilder builder)
     {
         builder.append(" inner join " );
         builder.append(query.getTableName(_joinClass)).append(" as ");
@@ -80,7 +84,7 @@ public class Join
     }
 
     /** The class of the table we're to join against. */
-    protected Class _joinClass;
+    protected Class<? extends PersistentRecord> _joinClass;
 
     /** The condition used to join in the new table. */
     protected SQLOperator _joinCondition;

src/java/com/samskivert/jdbc/depot/clause/Limit.java

@@ -22,15 +22,13 @@ package com.samskivert.jdbc.depot.clause;
 
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
-import java.util.Collection;
 
 import com.samskivert.jdbc.depot.ConstructedQuery;
 
 /**
  *  Represents a LIMIT/OFFSET clause, for pagination.
  */
-public class Limit
+public class Limit extends QueryClause
-    implements QueryClause
 {
     public Limit (int offset, int count)
     {
@@ -39,13 +37,7 @@ public class Limit
     }
 
     // from QueryClause
-    public Collection<Class> getClassSet ()
+    public void appendClause (ConstructedQuery<?> query, StringBuilder builder)
-    {
-        return null;
-    }
-
-    // from QueryClause
-    public void appendClause (ConstructedQuery query, StringBuilder builder)
     {
         builder.append(" limit ? offset ? ");
     }

src/java/com/samskivert/jdbc/depot/clause/OrderBy.java

@@ -22,7 +22,6 @@ package com.samskivert.jdbc.depot.clause;
 
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
-import java.util.Collection;
 
 import com.samskivert.jdbc.depot.ConstructedQuery;
 import com.samskivert.jdbc.depot.expression.ColumnExp;
@@ -31,8 +30,7 @@ import com.samskivert.jdbc.depot.expression.SQLExpression;
 /**
  *  Represents an ORDER BY clause.
  */
-public class OrderBy
+public class OrderBy extends QueryClause
-    implements QueryClause
 {
     /** Indicates the order of the clause. */
     public enum Order { ASC, DESC };
@@ -76,13 +74,7 @@ public class OrderBy
     }
 
     // from QueryClause
-    public Collection<Class> getClassSet ()
+    public void appendClause (ConstructedQuery<?> query, StringBuilder builder)
-    {
-        return null;
-    }
-
-    // from QueryClause
-    public void appendClause (ConstructedQuery query, StringBuilder builder)
     {
         builder.append(" order by ");
         for (int ii = 0; ii < _values.length; ii++) {

src/java/com/samskivert/jdbc/depot/clause/QueryClause.java

@@ -25,29 +25,36 @@ import java.sql.SQLException;
 import java.util.Collection;
 
 import com.samskivert.jdbc.depot.ConstructedQuery;
+import com.samskivert.jdbc.depot.PersistentRecord;
 
 /**
  * Represents a piece or modifier of an SQL query.
  */
-public interface QueryClause
+public abstract class QueryClause
 {
     /**
-     * Return a set of all persistent classes referenced by this clause.  Null may be returned if
+     * Return a set of all persistent classes referenced by this clause. The default implementation
-     * no classes are rererenced.
+     * returns null to indicate that no classes are rererenced.
      */
-    public Collection<Class> getClassSet ();
+    public Collection<Class<? extends PersistentRecord>> getClassSet ()
+    {
+        return null;
+    }
     
     /**
-     * Construct the SQL form of this query clause. The implementor is expected to call methods
+     * Construct the SQL form of this query clause. The implementor is expected to call methods on
-     * on the Query object to e.g. resolve current table abbreviations associated with classes.
+     * the Query object to e.g. resolve current table abbreviations associated with classes.
      */
-    public void appendClause (ConstructedQuery query, StringBuilder builder);
+    public abstract void appendClause (ConstructedQuery<?> query, StringBuilder builder);
 
     /**
      * Bind any objects that were referenced in the generated SQL.  For each ? that appears in the
      * SQL, precisely one parameter must be claimed and bound in this method, and argIdx
-     * incremented and returned.
+     * incremented and returned. The default implementation binds nothing.
      */
     public int bindArguments (PreparedStatement pstmt, int argIdx)
-        throws SQLException;
+        throws SQLException
+    {
+        return argIdx;
+    }
 }

src/java/com/samskivert/jdbc/depot/clause/Where.java

@@ -22,24 +22,22 @@ package com.samskivert.jdbc.depot.clause;
 
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
-import java.util.Arrays;
-import java.util.List;
 
 import com.samskivert.jdbc.depot.ConstructedQuery;
+import com.samskivert.jdbc.depot.PersistentRecord;
 import com.samskivert.jdbc.depot.clause.QueryClause;
 import com.samskivert.jdbc.depot.expression.ColumnExp;
 import com.samskivert.jdbc.depot.expression.ValueExp;
-import com.samskivert.jdbc.depot.operator.SQLOperator;
 import com.samskivert.jdbc.depot.operator.Conditionals.Equals;
 import com.samskivert.jdbc.depot.operator.Conditionals.IsNull;
 import com.samskivert.jdbc.depot.operator.Logic.And;
+import com.samskivert.jdbc.depot.operator.SQLOperator;
 
 /**
  * Represents a where clause: the condition can be any comparison operator or logical combination
  * thereof.
  */
-public class Where
+public class Where extends QueryClause
-    implements QueryClause
 {
     public Where (String index, Comparable value)
     {
@@ -88,13 +86,7 @@ public class Where
     }
 
     // from QueryClause
-    public List<Class> getClassSet()
+    public void appendClause (ConstructedQuery<?> query, StringBuilder builder)
-    {
-        return Arrays.asList(new Class[] { });
-    }
-
-    // from QueryClause
-    public void appendClause (ConstructedQuery query, StringBuilder builder)
     {
         builder.append(" where ");
         _condition.appendExpression(query, builder);

src/java/com/samskivert/jdbc/depot/expression/ColumnExp.java

@@ -24,6 +24,7 @@ import java.sql.PreparedStatement;
 import java.sql.SQLException;
 
 import com.samskivert.jdbc.depot.ConstructedQuery;
+import com.samskivert.jdbc.depot.PersistentRecord;
 
 /**
  * An expression identifying a column of a class, e.g. GameRecord.itemId. If no class is given,
@@ -33,7 +34,7 @@ public class ColumnExp
     implements SQLExpression
 {
     /** The table that hosts the column we reference, or null. */
-    final public Class pClass;
+    final public Class<? extends PersistentRecord> pClass;
 
     /** The name of the column we reference. */
     final public String pColumn;
@@ -43,7 +44,7 @@ public class ColumnExp
         this(null, column);
     }
 
-    public ColumnExp (Class c, String column)
+    public ColumnExp (Class<? extends PersistentRecord> c, String column)
     {
         super();
         pClass = c;
@@ -51,7 +52,7 @@ public class ColumnExp
     }
 
     // from SQLExpression
-    public void appendExpression (ConstructedQuery query, StringBuilder builder)
+    public void appendExpression (ConstructedQuery<?> query, StringBuilder builder)
     {
         if (pClass == null || query == null) {
             builder.append(pColumn);

src/java/com/samskivert/jdbc/depot/expression/SQLExpression.java

@@ -34,7 +34,7 @@ public interface SQLExpression
      * Construct the SQL form of this expression. The implementor is invited to call methods on the
      * Query object to e.g. resolve the current table abbreviations associated with classes.
      */
-    public void appendExpression (ConstructedQuery query, StringBuilder builder);
+    public void appendExpression (ConstructedQuery<?> query, StringBuilder builder);
 
     /**
      * Bind any objects that were referenced in the generated SQL.  For each ? that appears in the

src/java/com/samskivert/jdbc/depot/operator/Conditionals.java

@@ -25,6 +25,7 @@ import java.sql.SQLException;
 import java.util.Collection;
 
 import com.samskivert.jdbc.depot.ConstructedQuery;
+import com.samskivert.jdbc.depot.PersistentRecord;
 import com.samskivert.jdbc.depot.expression.ColumnExp;
 import com.samskivert.jdbc.depot.expression.SQLExpression;
 import com.samskivert.jdbc.depot.operator.SQLOperator.BinaryOperator;
@@ -45,7 +46,7 @@ public abstract class Conditionals
             this(new ColumnExp(null, pColumn));
         }
 
-        public IsNull (Class pClass, String pColumn)
+        public IsNull (Class<? extends PersistentRecord> pClass, String pColumn)
         {
             this(new ColumnExp(pClass, pColumn));
         }
@@ -161,12 +162,13 @@ public abstract class Conditionals
             this(new ColumnExp(null, pColumn), values.toArray(new Comparable[values.size()]));
         }
 
-        public In (Class pClass, String pColumn, Comparable... values)
+        public In (Class<? extends PersistentRecord> pClass, String pColumn, Comparable... values)
         {
             this(new ColumnExp(pClass, pColumn), values);
         }
 
-        public In (Class pClass, String pColumn, Collection<? extends Comparable> values)
+        public In (Class<? extends PersistentRecord> pClass, String pColumn,
+                   Collection<? extends Comparable> values)
         {
             this(new ColumnExp(pClass, pColumn), values.toArray(new Comparable[values.size()]));
         }