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https://issues.apache.org/jira/browse/FLINK-3444?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15261720#comment-15261720
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Till Rohrmann commented on FLINK-3444:
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What kind of cases would that be? I mean the pure var arg implementation is
also capable of finding the common super type for the provided set of elements.
Thus, I think we should be able to do the same.
Moreover, in case that the user provides a wrong {{Class<T>}} instance, then
the pure var arg method is called where the common super type is {{Object}}.
This is completely intransparent to the user and thus confusing. I think this
should be fixed by not allowing the compiler to compile these kind of programs
or by automatically inferring the common super type.
> env.fromElements relies on the first input element for determining the
> DataSet/DataStream type
> ----------------------------------------------------------------------------------------------
>
> Key: FLINK-3444
> URL: https://issues.apache.org/jira/browse/FLINK-3444
> Project: Flink
> Issue Type: Bug
> Components: DataSet API, DataStream API
> Affects Versions: 0.10.0, 1.0.0
> Reporter: Vasia Kalavri
> Fix For: 1.1.0
>
>
> The {{fromElements}} method of the {{ExecutionEnvironment}} and
> {{StreamExecutionEnvironment}} determines the DataSet/DataStream type by
> extracting the type of the first input element.
> This is problematic if the first element is a subtype of another element in
> the collection.
> For example, the following
> {code}
> DataStream<Event> input = env.fromElements(new Event(1, "a"), new SubEvent(2,
> "b"));
> {code}
> succeeds, while the following
> {code}
> DataStream<Event> input = env.fromElements(new SubEvent(1, "a"), new Event(2,
> "b"));
> {code}
> fails with "java.lang.IllegalArgumentException: The elements in the
> collection are not all subclasses of SubEvent".
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