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https://issues.apache.org/jira/browse/FLINK-10958?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16695633#comment-16695633
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ASF GitHub Bot commented on FLINK-10958:
----------------------------------------
sunjincheng121 commented on a change in pull request #7152: [FLINK-10958]
[table] Add overload support for user defined function
URL: https://github.com/apache/flink/pull/7152#discussion_r235627061
##########
File path:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/utils/UserDefinedFunctionUtils.scala
##########
@@ -719,19 +750,28 @@ object UserDefinedFunctionUtils {
* Compares parameter candidate classes with expected classes. If true, the
parameters match.
* Candidate can be null (acts as a wildcard).
*/
+ private def parameterTypeApplicable(candidate: Class[_], expected:
Class[_]): Boolean =
+ parameterTypeEquals(candidate, expected) ||
parameterTypeSubClassOf(candidate, expected)
+
Review comment:
I suggest remove `parameterTypeSubClassOf` and impl the
`parameterTypeApplicable` as follows:
```
parameterTypeEquals(candidate, expected) ||
((expected != null && expected.isAssignableFrom(candidate)) ||
expected.isPrimitive &&
Primitives.wrap(expected).isAssignableFrom(candidate) ||
// arrays
(candidate.isArray && expected.isArray &&
expected.getComponentType.isAssignableFrom(candidate.getComponentType)))
```
What do you think?
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> Add overload support for user defined function
> -----------------------------------------------
>
> Key: FLINK-10958
> URL: https://issues.apache.org/jira/browse/FLINK-10958
> Project: Flink
> Issue Type: Task
> Components: Table API & SQL
> Reporter: Dian Fu
> Assignee: Dian Fu
> Priority: Major
> Labels: pull-request-available
>
> 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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