[jira] [Commented] (FLINK-3002) Add an EitherType to the Java API

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-3002?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15863729#comment-15863729 ] 

ASF GitHub Bot commented on FLINK-3002:
---------------------------------------

Github user helfper commented on a diff in the pull request:

    https://github.com/apache/flink/pull/1371#discussion_r100800288
  
    --- Diff: flink-java/src/test/java/org/apache/flink/api/java/typeutils/EitherTypeInfoTest.java ---
    @@ -0,0 +1,58 @@
    +/*
    + * 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
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    + * 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;
    +
    +import org.apache.flink.api.common.typeinfo.BasicTypeInfo;
    +import org.apache.flink.api.java.tuple.Tuple2;
    +import org.apache.flink.util.TestLogger;
    +import org.junit.Test;
    +
    +import static org.junit.Assert.*;
    +
    +public class EitherTypeInfoTest extends TestLogger {
    +
    +	Either<Integer, String> intEither = Either.left(1);
    +	Either<Integer, String> stringEither = Either.right("boo");
    +	Either<Integer, Tuple2<Double, Long>> tuple2Either = Either.right(new Tuple2<Double, Long>(42.0, 2l));
    +
    +	@Test
    +	public void testEitherTypeEquality() {
    +		EitherTypeInfo<Integer, String> eitherInfo1 = new EitherTypeInfo<Integer, String>(
    +				BasicTypeInfo.INT_TYPE_INFO, BasicTypeInfo.STRING_TYPE_INFO);
    +
    +		EitherTypeInfo<Integer, String> eitherInfo2 = new EitherTypeInfo<Integer, String>(
    +				BasicTypeInfo.INT_TYPE_INFO, BasicTypeInfo.STRING_TYPE_INFO);
    +
    +		assertEquals(eitherInfo1, eitherInfo2);
    +		assertEquals(eitherInfo1.hashCode(), eitherInfo2.hashCode());
    +	}
    +
    +	@Test
    +	public void testEitherTypeInEquality() {
    +		EitherTypeInfo<Integer, String> eitherInfo1 = new EitherTypeInfo<Integer, String>(
    +				BasicTypeInfo.INT_TYPE_INFO, BasicTypeInfo.STRING_TYPE_INFO);
    +
    +		EitherTypeInfo<Integer, Tuple2<Double, Long>> eitherInfo2 = new EitherTypeInfo<Integer, Tuple2<Double, Long>>(
    +				BasicTypeInfo.INT_TYPE_INFO, new TupleTypeInfo<Tuple2<Double, Long>>(
    +				TypeExtractor.getForClass(Double.class), TypeExtractor.getForClass(String.class)));
    +
    +		assertNotEquals(eitherInfo1, eitherInfo2);
    +		assertNotEquals(eitherInfo1.hashCode(), eitherInfo2.hashCode());
    --- End diff --
    
    This assert seems conceptually wrong to me (even if it works in this specific case), as the contract for `hashCode` is `t1.equals(t2) => t1.hashCode() == t2.hashCode()`, so given `!t1.equals(t2)`, we can't actually conclude anything about their `hashCode`'s. I think it should be removed from the `master`.


> 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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