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https://issues.apache.org/jira/browse/BEAM-1336?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15978046#comment-15978046
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ASF GitHub Bot commented on BEAM-1336:
--------------------------------------
GitHub user kennknowles opened a pull request:
https://github.com/apache/beam/pull/2627
[BEAM-1336] Separate StateSpec and KeyedStateSpec
Before this change, almost all uses of state had a type variable that
existing only to support the esoteric use of a KeyedCombineFn in
a state cell. Now those cases use a more verbose form of KeyedStateSpec.
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---
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/kennknowles/beam StateSpec
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/beam/pull/2627.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 #2627
----
commit c05bda1a5922e18ab29022403f7b9e00f4cea941
Author: Kenneth Knowles <k...@google.com>
Date: 2017-04-21T03:46:37Z
Separate StateSpec and KeyedStateSpec
Before this change, almost all uses of state had a type variable that
existing only to support the esoteric use of a KeyedCombineFn in
a state cell. Now those cases use a more verbose form of KeyedStateSpec.
----
> A StateSpec that doesn't care about the key shouldn't be forced to declare it
> as type Object
> --------------------------------------------------------------------------------------------
>
> Key: BEAM-1336
> URL: https://issues.apache.org/jira/browse/BEAM-1336
> Project: Beam
> Issue Type: Improvement
> Components: sdk-java-core
> Reporter: Kenneth Knowles
> Assignee: Kenneth Knowles
> Priority: Minor
> Labels: starter
>
> In the state API as it exists today, if (as is almost often the case) you are
> writing a {{StateSpec<K, StateT>}} other than a {{KeyedCombiningState}} the
> key type is irrelevant and the user just has to write {{Object}} there. This
> was carried over from {{StateTag}} and is an artifact of the visitor pattern
> there and the difficulty of getting all the types to line up.
> I think simplifying the visitor pattern to be more of just a syntax traversal
> might alleviate the issue and allow us to drop this noise from the syntax.
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