Github user jacques-n commented on a diff in the pull request:
https://github.com/apache/drill/pull/466#discussion_r59574906
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/PlannerCallback.java
---
@@ -0,0 +1,59 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.drill.exec.planner;
+
+import java.util.Collection;
+
+import org.apache.calcite.plan.RelOptPlanner;
+
+/**
+ * A callback that StoragePlugins can initialize to allow further
configuration
+ * of the Planner at initialization time. Examples could be to allow
adding lattices,
+ * materializations or additional traits to the planner that will be used
in
+ * planning.
+ */
+public abstract class PlannerCallback {
--- End diff --
Generally, I think up through Java 7, trying to do functional programming
creates unmaintainable and hard to understand code. I've seen some projects
which especially suffer from this. If we deprecated Java 7, I'd likely change
my tune. I'm a fan of functional programming when the language has good support
for it.
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