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https://issues.apache.org/jira/browse/FLINK-2788?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15172718#comment-15172718
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ASF GitHub Bot commented on FLINK-2788:
---------------------------------------
GitHub user StephanEwen opened a pull request:
https://github.com/apache/flink/pull/1744
[FLINK-2788] [apis] Add TypeHint class to allow type-safe generic type
parsing
This adds the `TypeHint` as a type-safe way to create `TypeInformation` for
generic types. I think it should gradually replace the `TypeInfoParser`.
Generic type infos can be created via
```java
TypeInformation<Tuple2<String, Double>> info = TypeInformation.of(new
TypeHint<Tuple2<String, Double>>() {});
```
This creates an inline class that captures the generic parameters, and
fetches them via the TypeExtractor.
*This pull request is in preparation for improving the streaming example.*
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/StephanEwen/incubator-flink typehint
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/1744.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 #1744
----
commit c4957ce198935a390e838ca74a610108af122ad8
Author: Stephan Ewen <[email protected]>
Date: 2016-02-29T18:24:34Z
[FLINK-2788] [apis] Add TypeHint class to allow type-safe generic type
parsing
----
> Add type hint with TypeExtactor call on Hint Type
> -------------------------------------------------
>
> Key: FLINK-2788
> URL: https://issues.apache.org/jira/browse/FLINK-2788
> Project: Flink
> Issue Type: Improvement
> Components: Core
> Affects Versions: 0.10.0
> Reporter: Stephan Ewen
> Assignee: Stephan Ewen
> Fix For: 1.0.0
>
>
> As per discussion with [~aljoscha]
> A very good and type safe way to supply type hints would be the following:
> Define a hint class that takes a generic parameter.
> {code}
> public abstract class TypeHint<T> {}
> {code}
> The hints would have the following method:
> {code}
> public DataSet<T> returns(TypeHint<T> hint);
> {code}
> It would be used like this:
> {code}
> DataSet<Sting> data = ...;
> data
> .flatMap( (String str, Collector<Integer> out) -> out.collect(str.length())
> )
> .returns( new TypeHint<Integer>() {})
> {code}
> This would create an inline subclass of the hint, from which the type could
> be extracted. The generics would ensure that it is typesafe.
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