Github user twalthr commented on a diff in the pull request:
https://github.com/apache/flink/pull/3389#discussion_r105186593
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/utils/UserDefinedFunctionUtils.scala
---
@@ -139,9 +143,35 @@ object UserDefinedFunctionUtils {
s"Function class '${function.getClass.getCanonicalName}' does not
implement at least " +
s"one method named 'eval' which is public, not abstract and " +
s"(in case of table functions) not static.")
- } else {
- methods
}
+
+ verifyScalaVarargsAnnotation(methods)
+ methods
+ }
+
+ /**
+ * If users specified an @varargs, Scala will generate two methods
indeed.
+ * If there does not exist corresponding varargs method of the Seq
method,
+ * we will throw an ValidationException.
+ */
+ def verifyScalaVarargsAnnotation(methods: Array[Method]) = {
+ methods.foreach(method => {
+ val signatures = method.getParameterTypes
+ if (signatures.nonEmpty &&
+ signatures.last.getName.equals("scala.collection.Seq") &&
--- End diff --
I think this condition is too strict. It wouldn't allow `Seq`s in functions
which is one of the most important classes in Scala. This does not work right
now:
```
object Func16 extends ScalarFunction {
def eval(a: Seq[String]): String = {
a.mkString(", ")
}
}
```
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