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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-1458) Interfaces and abstract classes are not valid types
Date Thu, 05 Feb 2015 11:04:34 GMT

    [ https://issues.apache.org/jira/browse/FLINK-1458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14307059#comment-14307059
] 

ASF GitHub Bot commented on FLINK-1458:
---------------------------------------

Github user aljoscha closed the pull request at:

    https://github.com/apache/flink/pull/357


> Interfaces and abstract classes are not valid types
> ---------------------------------------------------
>
>                 Key: FLINK-1458
>                 URL: https://issues.apache.org/jira/browse/FLINK-1458
>             Project: Flink
>          Issue Type: Bug
>            Reporter: John Sandiford
>            Assignee: Aljoscha Krettek
>
> I don't know whether this is by design or is a bug, but I am having trouble working with
DataSet and traits in scala which is a major limitation.  A simple example is shown below.
 
> Compile time warning is 'Type Main.SimpleTrait has no fields that are visible from Scala
Type analysis. Falling back to Java Type Analysis...'
> Run time error is 'Interfaces and abstract classes are not valid types: interface Main$SimpleTrait'
> Regards, John
>  val env = ExecutionEnvironment.getExecutionEnvironment
>   trait SimpleTrait {
>     def contains(x: String): Boolean
>   }
>   class SimpleClass extends SimpleTrait {
>     def contains(x: String) = true
>   }
>   val data: DataSet[Double] = env.fromElements(1.0, 2.0, 3.0, 4.0)
>   def f(data: DataSet[Double]): DataSet[SimpleTrait] = {
>     data.mapPartition(iterator => {
>       Iterator(new SimpleClass)
>     })
>   }
>   val g = f(data)
>   g.print()
>   env.execute("Simple example")



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