public abstract class ContextualEvalFunc<T>
An abstract class which enables UDFs to store instance properties
on the front end which will be available on the back end.
For example, you can override the onSchemaReady hook method to set properties
at front-end (i.e. at launch time) which will be available when exec() is
called (on the workers themselves.
Nested Class Summary
Nested classes/interfaces inherited from class org.apache.pig.EvalFunc
Fields inherited from class org.apache.pig.EvalFunc
Hook method, called once the input and output schema are prepared.
Subclasses may override to set properties on the front end (i.e. at script
run time) that may be played with later (e.g. at execution time).
Child classes must (a) call super.onReady(in_schema, out_schema) so
that the hook chains, and (b) not mess with the schema.
in_schema - input schema
out_schema - output schema
public org.apache.pig.impl.logicalLayer.schema.Schema outputSchema(org.apache.pig.impl.logicalLayer.schema.Schema in_schema)
Override outputSchema only to add the onSchemaReady hook method. In all
other respects delegates to the superclass outputSchema preparation.