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https://issues.apache.org/jira/browse/PIG-2547?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13257649#comment-13257649
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Dmitriy V. Ryaboy commented on PIG-2547:
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Bumping for review
> Easier UDFs: Convenient EvalFunc super-classes
> ----------------------------------------------
>
> Key: PIG-2547
> URL: https://issues.apache.org/jira/browse/PIG-2547
> Project: Pig
> Issue Type: New Feature
> Reporter: Bill Graham
> Assignee: Bill Graham
> Labels: 0.10_blocker
> Fix For: 0.10.0, 0.11
>
> Attachments: PIG_2547.1.patch, PIG_2547.2.patch
>
>
> We've got a few abstract extensions of EvalFunc that make life easier. If
> people are interested we can push said classes into Pig.
> There are 3 classes, each extending the next. Class naming is all TBD.
> * {{TypedOutputEvalFunc<OUT>}} - Implements {{public Schema
> outputSchema(Schema input)}} based on the generic type of the subclass.
> Provides common helper validation functions which increment counters for good
> and bad Tuple data passed. Useful where the input to be worked on is a tuple
> of size N or greater.
> * {{PrimitiveEvalFunc<IN, OUT>}} - Same as above with helper validation
> allowing the ability it subclass and just implement {{public OUT exec(IN
> input)}}, where IN and OUT are primitives. Useful when the input is a single
> primitive in position 0 of a tuple.
> * {{FunctionWrapperEvalFunc}} - Wraps a Guava Function implementation
> (http://guava-libraries.googlecode.com/svn/trunk/javadoc/com/google/common/base/Function.html)
> and allows UDFs to be used in Pig scripts like so, where {{MyFunction}} is a
> class that implements {{Function}}:
> {noformat}
> DEFINE myUdf org.apache.pig.FunctionWrapperEvalFunc('MyFunction')
> {noformat}
>
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