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Posted to dev@kafka.apache.org by "ASF GitHub Bot (JIRA)" <ji...@apache.org> on 2017/01/18 22:17:26 UTC
[jira] [Commented] (KAFKA-4672) KIP-100 api changes break Java 8
lambda expressions in some cases
[ https://issues.apache.org/jira/browse/KAFKA-4672?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15828861#comment-15828861 ]
ASF GitHub Bot commented on KAFKA-4672:
---------------------------------------
GitHub user xvrl opened a pull request:
https://github.com/apache/kafka/pull/2402
KAFKA-4672 fix source compatibility for lambda expressions
please cherry-pick into 0.10.2.x
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/xvrl/kafka lambdas-oh-my
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/kafka/pull/2402.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #2402
----
commit 070af889c64c2e78b458978c448b643fa3363a9b
Author: Xavier Léauté <xa...@confluent.io>
Date: 2017-01-18T21:53:10Z
KAFKA-4672 fix source compatibility for lambda expressions
----
> KIP-100 api changes break Java 8 lambda expressions in some cases
> ------------------------------------------------------------------
>
> Key: KAFKA-4672
> URL: https://issues.apache.org/jira/browse/KAFKA-4672
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Affects Versions: 0.10.2.0
> Reporter: Xavier Léauté
> Assignee: Xavier Léauté
> Fix For: 0.10.2.0
>
>
> Variance changes introduced in KIP-100 cause compilation failures with lambda expression in Java 8.
> To my knowledge this only affects methods taking suppliers of functions
> KStreams.transform(TransformerSupplier<...>, String...)
> KStreams.transformValues(ValueTransformerSupplier<...>)
> prior to the changes it was possible to write
> streams.transform(MyTransformer::new)
> streams.transformValues(MyValueTransformer::new)
> where MyTransformer and MyValueTransformer extend Transformer and ValueTransformer respectively.
> After the changes the Java compiler is unable to infer correct return types for the lambda expression.
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