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https://issues.apache.org/jira/browse/FLINK-1159?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15206440#comment-15206440
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ASF GitHub Bot commented on FLINK-1159:
---------------------------------------
Github user stefanobaghino commented on the pull request:
https://github.com/apache/flink/pull/1704#issuecomment-199837531
A quick status update: unfortunately I have had no time to work on this in
the past week, I plan to get back to the fixes on Thursday or Friday.
In the meanwhile, I have a small doubt on the usage of `Iterator`: they are
indeed very good to allow the user to have access both to the whole
`DataSet`/`DataStream` or accessing it one item at a time; however, they are
not particularly useful when used with the case-style partial functions: they
offer an edge to de-structure a single item like a tuple or a collection like
`Seq` (e.g. using the `_ +: rest` operator to only get the item after the
first).
Are we sure we want to keep the `Iterator`? Is there an advantage in having
an `Iterator` with this extension? I see to possible solutions:
1. the easy one: having two methods, one materializing the `Iterator` into
a collection and another one accessing the items one a time: the only issue
with this would be the need to have to methods with distinct names (otherwise
we would be back to square one); this means the user can use the case-style
functions to destructure the collection or each item separately; otherwise we
can
2. adopt a slightly more sophisticated solution: wrap the `Iterator` in a
`Stream`, which is lazy but also fully destructurable in case-style functions
(e.g.: using the `#::` operator). This would require some work as the
`Iterator` is stateful with regards of the traversal while the `Stream` is not
and we can't just use a naive solution or the semantic difference could lead to
some nasty bugs in user code.
> Case style anonymous functions not supported by Scala API
> ---------------------------------------------------------
>
> Key: FLINK-1159
> URL: https://issues.apache.org/jira/browse/FLINK-1159
> Project: Flink
> Issue Type: Bug
> Components: Scala API
> Reporter: Till Rohrmann
> Assignee: Stefano Baghino
>
> In Scala it is very common to define anonymous functions of the following form
> {code}
> {
> case foo: Bar => foobar(foo)
> case _ => throw new RuntimeException()
> }
> {code}
> These case style anonymous functions are not supported yet by the Scala API.
> Thus, one has to write redundant code to name the function parameter.
> What works is the following pattern, but it is not intuitive for someone
> coming from Scala:
> {code}
> dataset.map{
> _ match{
> case foo:Bar => ...
> }
> }
> {code}
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