Easier UDFs: Convenient EvalFunc super-classes
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Key: PIG-2547
URL: https://issues.apache.org/jira/browse/PIG-2547
Project: Pig
Issue Type: New Feature
Reporter: Bill Graham
Assignee: Bill Graham
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 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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