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https://issues.apache.org/jira/browse/FLINK-1458?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14303187#comment-14303187
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ASF GitHub Bot commented on FLINK-1458:
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Github user aljoscha commented on the pull request:
https://github.com/apache/flink/pull/357#issuecomment-72642370
You're right.
> 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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