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https://issues.apache.org/jira/browse/FLINK-8863?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16508298#comment-16508298
]
ASF GitHub Bot commented on FLINK-8863:
---------------------------------------
Github user twalthr commented on a diff in the pull request:
https://github.com/apache/flink/pull/6090#discussion_r194456301
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/descriptors/ClassTypeDescriptor.scala
---
@@ -0,0 +1,71 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.table.descriptors
+
+import scala.collection.mutable.ArrayBuffer
+
+/**
+ * Descriptor for a class type.
--- End diff --
Descriptors might become public API in the future. We should add more
comments and have a more fluent method scheme. I would propose something like:
```
ClassInstance().of("org.example.MyFunction")
.parameter("12.0")
.parameter("DOUBLE", "12")
.parameter(Types.DOUBLE, 12)
```
I think we don't need to expose the primitive type descriptor. We can use
it internally though. Alternatively, we could also move functionality to
`org.apache.flink.table.descriptors.DescriptorProperties` if applicable.
> Add user-defined function support in SQL Client
> -----------------------------------------------
>
> Key: FLINK-8863
> URL: https://issues.apache.org/jira/browse/FLINK-8863
> Project: Flink
> Issue Type: Sub-task
> Components: Table API & SQL
> Reporter: Timo Walther
> Assignee: Xingcan Cui
> Priority: Major
>
> This issue is a subtask of part two "Full Embedded SQL Client" of the
> implementation plan mentioned in
> [FLIP-24|https://cwiki.apache.org/confluence/display/FLINK/FLIP-24+-+SQL+Client].
>
> It should be possible to declare user-defined functions in the SQL client.
> For now, we limit the registration to classes that implement
> {{ScalarFunction}}, {{TableFunction}}, {{AggregateFunction}}. Functions that
> are implemented in SQL are not part of this issue.
> I would suggest to introduce a {{functions}} top-level property. The
> declaration could look similar to:
> {code}
> functions:
> - name: testFunction
> from: class <-- optional, default: class
> class: org.my.MyScalarFunction
> constructor: <-- optional, needed for certain types of functions
> - 42.0
> - class: org.my.Class <-- possibility to create objects via properties
> constructor:
> - 1
> - true
> - false
> - "whatever"
> - type: INT
> value: 1
> {code}
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