EvalFunc returnType is wrong for generic subclasses
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Key: PIG-1288
URL: https://issues.apache.org/jira/browse/PIG-1288
Project: Pig
Issue Type: Bug
Components: impl
Affects Versions: 0.7.0
Reporter: Daniel Dai
>From Garrett Buster Kaminaga:
The EvalFunc constructor has code to determine the return type of the function.
This walks up the object hierarchy until it encounters EvalFunc, then calls
getActualTypeArguments and extracts type
param 0.
However, if the user class is itself a generic extension of EvalFunc, then the
returned object is not the correct type,
but a TypeVariable.
Example:
class MyAbstractEvalFunc<T> extends EvalFunc<T> ...
class MyEvalFunc extends MyAbstractEvalFunc<String> ...
when MyEvalFunc() is called, inside EvalFunc constructor the return type is set
to a TypeVariable rather than
String.class.
The workaround we've implemented is for the MyAbstractEvalFunc<T> to determine
*its* type parameters using code
similar to that in the EvalFunc constructor, and then reset protected data
member returnType manually in the
MyAbstractEvalFunc constructor. (though this has the same drawback of not
working if someone then extends
MyAbstractEvalFunc)
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