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Pei He commented on BEAM-247: ----------------------------- Closing as work as intended. However, there are documents about Combine that are out of sync. And, in general we need more tests to cover accessing PTransforms from other packages. > CombineFn's only definable/usable inside sdk.transforms package > --------------------------------------------------------------- > > Key: BEAM-247 > URL: https://issues.apache.org/jira/browse/BEAM-247 > Project: Beam > Issue Type: Bug > Components: sdk-java-core > Reporter: Ben Chambers > Assignee: Pei He > Priority: Critical > > {code:java} > public abstract static class CombineFn<InputT, AccumT, OutputT> > extends AbstractGlobalCombineFn<InputT, AccumT, OutputT> { /* ... */ } > abstract static class AbstractGlobalCombineFn<InputT, AccumT, OutputT> > implements GlobalCombineFn<InputT, AccumT, OutputT>, Serializable { /* ... > */ } > {code} > Since {{AbstractGlobalCombineFn}} is package protected (and therefore not > visible outside of the {{transform}} package, it is not possible to cast any > class that extends {{CombineFn}} to a {{GlobalCombineFn}} outside of this > package. > This prevents applying existing {{CombineFns}} directly (such as > {{Combine.perKey(new Sum.SumIntegersFn())}}, as used in our documentation) > and also means that a user cannot define their own {{CombineFn}} unless they > put them in the {{transform}} package. -- This message was sent by Atlassian JIRA (v6.3.4#6332)