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https://issues.apache.org/jira/browse/FLINK-10958?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16694378#comment-16694378
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ASF GitHub Bot commented on FLINK-10958:
----------------------------------------
dianfu opened a new pull request #7152: [FLINK-10958] [table] Add overload
support for user defined function
URL: https://github.com/apache/flink/pull/7152
## What is the purpose of the change
*This pull request adds the overload support for user defined function.*
## Brief change log
- *add logical in UserDefinedFunctionUtil#getUserDefinedMethod which
identifies the methods which are more applicable than others when multiple
methods are applicable.*
## Verifying this change
This change added tests and can be verified as follows:
- *Added test that validates that overload take effects*
## Does this pull request potentially affect one of the following parts:
- Dependencies (does it add or upgrade a dependency): (no)
- The public API, i.e., is any changed class annotated with
`@Public(Evolving)`: (no)
- The serializers: (no)
- The runtime per-record code paths (performance sensitive): (no)
- Anything that affects deployment or recovery: JobManager (and its
components), Checkpointing, Yarn/Mesos, ZooKeeper: (no)
- The S3 file system connector: (no)
## Documentation
- Does this pull request introduce a new feature? (no)
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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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