Github user sunjincheng121 commented on a diff in the pull request:
https://github.com/apache/flink/pull/4105#discussion_r121321436
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/functions/utils/UserDefinedFunctionUtils.scala
---
@@ -329,6 +337,41 @@ object UserDefinedFunctionUtils {
}
}
+
+ /**
+ * Internal method of AggregateFunction#getAccumulatorType() that does
some pre-checking
+ * and uses [[TypeExtractor]] as default return type inference.
+ */
+ def getAccumulatorTypeOfAggregateFunction(
+ aggregateFunction: AggregateFunction[_, _],
--- End diff --
Can we abstract a method according ` getAccumulatorTypeOfAggregateFunction`
and `getResultTypeOfAggregateFunction`. just like follows:
```
def getTypeByMethodOrTypeExtractor(
aggregateFunction: AggregateFunction[_, _],
clazz: Class[_],
methodName: String,
candidateType: TypeInformation[_] = null): TypeInformation[_] = {
val resultType = try {
val method: Method = aggregateFunction.getClass.getMethod(methodName)
method.invoke(aggregateFunction).asInstanceOf[TypeInformation[_]]
} catch {
case _: NoSuchMethodException => null
case ite: Throwable => throw new TableException("Unexpected
exception:", ite)
}
if (resultType != null) {
resultType
} else if(candidateType != null) {
candidateType
} else {
try {
TypeExtractor.createTypeInfo(clazz).asInstanceOf[TypeInformation[_]]
} catch {
case ite: InvalidTypesException =>
throw new TableException(
s"Cannot infer type of $clazz" +
s"You can override AggregateFunction.$methodName to specify the
type.", ite)
}
}
}
```
I'm not sure whether it is the best way, Please let me know what you think?
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