[jira] [Commented] (FLINK-7194) Add getResultType and getAccumulatorType to AggregateFunction

["Ruidong Li (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-7194?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16089419#comment-16089419 ] 

Ruidong Li commented on FLINK-7194:
-----------------------------------

[~fhueske]I agree to your suggestion, but the {{getResultType()}} in {{ScalarFunction}} is different from  {{TableFunction}} and {{AggregateFunction}}, what about if we put a ban on overloading {{eval()}} in {{ScalarFunction}}? That will result in better consistence.

> Add getResultType and getAccumulatorType to AggregateFunction
> -------------------------------------------------------------
>
>                 Key: FLINK-7194
>                 URL: https://issues.apache.org/jira/browse/FLINK-7194
>             Project: Flink
>          Issue Type: Improvement
>          Components: Table API & SQL
>    Affects Versions: 1.4.0
>            Reporter: Fabian Hueske
>
> FLINK-6725 and FLINK-6457 proposed to remove methods with default implementations such as {{getResultType()}}, {{toString()}}, or {{requiresOver()}} from the base classes of user-defined methods (UDF, UDTF, UDAGG) and instead offer them as contract methods which are dynamically 
> In PR [#3993|https://github.com/apache/flink/pull/3993] I argued that these methods have a fixed signature (in contrast to the {{eval()}}, {{accumulate()}} and {{retract()}} methods) and should be kept in the classes. For users that don't need these methods, this doesn't make a difference because the methods are not abstract and have a default implementation. For users that need to override the methods it makes a difference, because they get IDE and compiler support when overriding them and the cannot get the signature wrong.
> Consequently, I propose to add {{getResultType()}} and {{getAccumulatorType()}} as methods with default implementation to {{AggregateFunction}}. This will make the interface of {{AggregateFunction}} more consistent with {{ScalarFunction}} and {{TableFunction}}.
> What do you think [~shaoxuan], [~RuidongLi] and [~jark]?



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