Github user godfreyhe commented on a diff in the pull request:
https://github.com/apache/flink/pull/3176#discussion_r100478286
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/UserDefinedFunction.scala
---
@@ -24,4 +24,19 @@ package org.apache.flink.table.functions
* User-defined functions must have a default constructor and must be
instantiable during runtime.
*/
trait UserDefinedFunction {
--- End diff --
The Scala wrapper class can be abstract class.
MathTrait.scala
```Scala
trait MathTrait {
def sum(x: Int, y: Int) = x + y
}
```
MathTraitWrapper.scala
```Scala
abstract class MathTraitWrapper extends MathTrait {
}
```
JavaMath.java
```Java
public class JavaMath extends MathTraitWrapper {
public static void main(String[] args) {
new JavaMath();
}
public JavaMath() {
System.out.println(sum(2, 2));
}
}
```
This code works as expected, printing the number 4 when it is run.
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