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https://issues.apache.org/jira/browse/FLINK-1245?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14226688#comment-14226688
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ASF GitHub Bot commented on FLINK-1245:
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Github user StephanEwen commented on the pull request:
https://github.com/apache/incubator-flink/pull/203#issuecomment-64698910
I like the direction of this pull request. Here are some thought what we
could improve:
- Keeping the UnknownTypeInfo all the way and actually trying to work
with it will shadow problems. At much later points, when someone tries to use a
POJO field on the type info, an error will occur, at a point that is
disconnected from the source of the problem.
- How about we rename the `UnknownTypeInfo` to `MissingTypeInfo` and use
it only as a place-holder for the `returns()` hint method, which exchanges that
type info by the proper one.
- We could make sure that type extraction failures are recognized early,
by having the `getType()` method on the DataSet throw an error if only a
`MissingTypeInfo` exists.
- Getting Generic Lambdas to run with this may not be a good idea. This
goes against my original suggestion to keep this for the purpose of local
development with OracleJDK, but in hind-sight, I think things will get quite
intransparent to reason about and hard to maintain/debug/fix.
> Introduce TypeHints for Java API operators
> ------------------------------------------
>
> Key: FLINK-1245
> URL: https://issues.apache.org/jira/browse/FLINK-1245
> Project: Flink
> Issue Type: Improvement
> Components: Java API
> Reporter: Timo Walther
> Assignee: Timo Walther
>
> Due to type extraction issues with Java 8 Lambdas and many users with type
> erasure issues, TypeHints need to be introduced.
> The whole discussion can be found on the mailing list:
> http://mail-archives.apache.org/mod_mbox/flink-dev/201410.mbox/%[email protected]%3E
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