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From "Stephan Ewen (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-3042) Define a way to let types create their own TypeInformation
Date Wed, 20 Jul 2016 11:52:20 GMT

    [ https://issues.apache.org/jira/browse/FLINK-3042?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15385721#comment-15385721
] 

Stephan Ewen commented on FLINK-3042:
-------------------------------------

Slightly more sophisticated, for generic types could be 

@TypeInfo(MyTypeInfoFactory.class)
public class MyOptionType<T> {
    ....
}

public class MyTypeInfoFactory<T> extends TypeInfoFactory<MyType<T>> {

    public TypeInformation<MyType<T>> createTypeInfo(Map<String, TypeInformation<?>>
genericParameters) {
        return new MyTypeInfo(genericParameters.get("T");
    }
}

> Define a way to let types create their own TypeInformation
> ----------------------------------------------------------
>
>                 Key: FLINK-3042
>                 URL: https://issues.apache.org/jira/browse/FLINK-3042
>             Project: Flink
>          Issue Type: Improvement
>          Components: Core
>    Affects Versions: 0.10.0
>            Reporter: Stephan Ewen
>             Fix For: 1.0.0
>
>
> Currently, introducing new Types that should have specific TypeInformation requires
>   - Either integration with the TypeExtractor
>   - Or manually constructing the TypeInformation (potentially at every place) and using
type hints everywhere.
> I propose to add a way to allow classes to create their own TypeInformation (like a static
method "createTypeInfo()").
> To support generic nested types (like Optional / Either), the type extractor would provide
a Map of what generic variables map to what types (deduced from the input). The class can
use that to create the correct nested TypeInformation (possibly by calling the TypeExtractor
again, passing the Map of generic bindings).



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