[jira] [Created] (FLINK-13580) Add overload support for user defined function to blink-planner

["Jingsong Lee (JIRA)" <ji...@apache.org>]

Jingsong Lee created FLINK-13580:
------------------------------------

             Summary: Add overload support for user defined function to blink-planner
                 Key: FLINK-13580
                 URL: https://issues.apache.org/jira/browse/FLINK-13580
             Project: Flink
          Issue Type: New Feature
          Components: Table SQL / Planner
            Reporter: Jingsong Lee
             Fix For: 1.10.0


Currently overload is not supported in user defined function and given the following UDF
{code:java}
class Func21 extends ScalarFunction {
  def eval(p: People): String = {
    p.name
  }

  def eval(p: Student): String = {
    "student#" + p.name
  }
}

class People(val name: String)

class Student(name: String) extends People(name)

class GraduatedStudent(name: String) extends Student(name)
{code}
Queries such as the following will compile failed with error msg "Found multiple 'eval' methods which match the signature."

 
{code:java}
val udf = new Func21
val table = ...
table.select(udf(new GraduatedStudent("test"))) {code}
That's because overload is not supported in user defined function currently. I think it will make sense to support overload following the java language specification in section [15.2|https://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.12].

 



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