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From: stefanobaghino <git@git.apache.org>
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Subject: [GitHub] flink pull request: [FLINK-1159] Case style anonymous
 functions no...
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Message-Id: <20160314125632.E9CC9DFAEC@git1-us-west.apache.org>
Date: Mon, 14 Mar 2016 12:56:32 +0000 (UTC)

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

    https://github.com/apache/flink/pull/1704#discussion_r55995517
  
    --- Diff: flink-scala/src/main/scala/org/apache/flink/api/scala/extensions/package.scala ---
    @@ -0,0 +1,201 @@
    +/*
    + * 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.scala
    +
    +import org.apache.flink.api.common.typeinfo.TypeInformation
    +import org.apache.flink.api.scala.extensions.acceptPartialFunctions._
    +
    +import scala.reflect.ClassTag
    +
    +package object extensions {
    +
    +  /**
    +    * acceptPartialFunctions extends the original DataSet with methods with unique names
    +    * that delegate to core higher-order functions (e.g. `map`) so that we can work around
    +    * the fact that overloaded methods taking functions as parameters can't accept partial
    +    * functions as well. This enables the possibility to directly apply pattern matching
    +    * to decompose inputs such as tuples, case classes and collections.
    +    *
    +    * e.g.
    +    * {{{
    +    *   object Main {
    +    *     import org.apache.flink.api.scala.extensions._
    +    *     case class Point(x: Double, y: Double)
    +    *     def main(args: Array[String]): Unit = {
    +    *       val env = ExecutionEnvironment.getExecutionEnvironment
    +    *       val ds = env.fromElements(Point(1, 2), Point(3, 4), Point(5, 6))
    +    *       ds.filterWith {
    +    *         case Point(x, _) => x > 1
    +    *       }.reduceWith {
    +    *         case (Point(x1, y1), (Point(x2, y2))) => Point(x1 + y1, x2 + y2)
    +    *       }.mapWith {
    +    *         case Point(x, y) => (x, y)
    +    *       }.flatMapWith {
    +    *         case (x, y) => Seq('x' -> x, 'y' -> y)
    +    *       }.groupingBy {
    +    *         case (id, value) => id
    +    *       }
    +    *     }
    +    *   }
    +    * }}}
    +    *
    +    */
    +  implicit def acceptPartialFunctionsOnDataSet[T: TypeInformation](ds: DataSet[T]): OnDataSet[T] =
    --- End diff --
    
    I've tried but the implicit resolution doesn't seem to be smart enough to recognize which overloaded implicit definition to pick, so I had to fall back to this. I can make a couple of attempts using a common object with several methods or perhaps using type classes.


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