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https://issues.apache.org/jira/browse/FLINK-3002?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15010660#comment-15010660
]
ASF GitHub Bot commented on FLINK-3002:
---------------------------------------
Github user tillrohrmann commented on a diff in the pull request:
https://github.com/apache/flink/pull/1371#discussion_r45180256
--- Diff:
flink-java/src/main/java/org/apache/flink/api/java/typeutils/runtime/EitherSerializer.java
---
@@ -0,0 +1,194 @@
+/*
+ * 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.flink.api.java.typeutils.runtime;
+
+import java.io.IOException;
+
+import org.apache.flink.api.common.typeutils.TypeSerializer;
+import org.apache.flink.api.java.typeutils.Either;
+import org.apache.flink.core.memory.DataInputView;
+import org.apache.flink.core.memory.DataOutputView;
+
+/**
+ * A {@link TypeSerializer} for the {@ link Either} type of the Java class.
+ *
+ * @param <L> the Left value type
+ * @param <R> the Right value type
+ */
+public class EitherSerializer<L, R> extends TypeSerializer<Either<L, R>> {
+
+ private static final long serialVersionUID = 1L;
+
+ private final Class<Either<L, R>> typeClass;
+
+ private final TypeSerializer<L> leftSerializer;
+
+ private final TypeSerializer<R> rightSerializer;
+
+ public EitherSerializer(Class<Either<L, R>> typeClass,
TypeSerializer<L> leftSerializer, TypeSerializer<R> rightSerializer) {
+ this.typeClass = typeClass;
+ this.leftSerializer = leftSerializer;
+ this.rightSerializer = rightSerializer;
+ }
+
+ @Override
+ public boolean isImmutableType() {
+ return true;
+ }
+
+ @Override
+ public TypeSerializer<Either<L, R>> duplicate() {
+ TypeSerializer<L> duplicateLeft = leftSerializer.duplicate();
+ TypeSerializer<R> duplicateRight = rightSerializer.duplicate();
+
+ if ((leftSerializer != duplicateLeft) || (rightSerializer !=
duplicateRight)) {
+ // stateful
+ return new EitherSerializer<L, R>(typeClass,
duplicateLeft, duplicateRight);
+ }
+ else {
+ return this;
+ }
+ }
+
+
+ @Override
+ public Either<L, R> createInstance() {
+ // We arbitrarily always create a Left value instance.
+ return Either.left(leftSerializer.createInstance());
--- End diff --
I would rather create a `Either.Right` instance per default. The reason is
that `Either.Left` is used for failures (by convention) and `Either.Right` is
akin to `Some`.
> Add an EitherType to the Java API
> ---------------------------------
>
> Key: FLINK-3002
> URL: https://issues.apache.org/jira/browse/FLINK-3002
> Project: Flink
> Issue Type: New Feature
> Components: Java API
> Affects Versions: 0.10.0
> Reporter: Stephan Ewen
> Assignee: Vasia Kalavri
> Fix For: 1.0.0
>
>
> Either types are recurring patterns and should be serialized efficiently, so
> it makes sense to add them to the core Java API.
> Since Java does not have such a type as of Java 8, we would need to add our
> own version.
> The Scala API handles the Scala Either Type already efficiently. I would not
> use the Scala Either Type in the Java API, since we are trying to get the
> {{flink-java}} project "Scala free" for people that don't use Scala and o not
> want to worry about Scala version matches and mismatches.
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