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https://issues.apache.org/jira/browse/PIG-2421?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13445402#comment-13445402
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Raghu Angadi commented on PIG-2421:
-----------------------------------
# +1 for making a context available (current UDFContext is not available for
UDFs).
#* use case: I want to be able to this write UDF 'NullIfMissing()' define
this way: {code}
a = load 'input' as (p:(one, two, three), q:int);
b = foreach a generate NullIfMissing(p);
describe b;
{t: (one: bytearray, two: bytearray, three: bytearray)}
-- NullIfMissing Returns
-- (null, null, null) if 'p' is null
-- (x, y, z), if p == (x, y, z)
-- (x, y, null) if p == (x, y)
{code}
# making conf available (readonly is sufficient, and probably preferred since a
UDF context can used to store any state).
> EvalFuncs need redesigned
> -------------------------
>
> Key: PIG-2421
> URL: https://issues.apache.org/jira/browse/PIG-2421
> Project: Pig
> Issue Type: New Feature
> Components: impl
> Affects Versions: 0.11
> Reporter: Alan Gates
> Assignee: Alan Gates
> Attachments: examples.patch, PIG-newudf.patch
>
>
> The current EvalFunc interface (and associated Algebraic and Accumulator
> interfaces) have grown unwieldy. In particular, people have noted the
> following issues:
> # Writing a UDF requires a lot of boiler plate code.
> # Since UDFs always pass a tuple, users are required to manage their own type
> checking for input.
> # Declaring schemas for output data is confusing.
> # Writing a UDF that accepts multiple different parameters (using
> getArgToFuncMapping) is confusing.
> # Using Algebraic and Accumulator interfaces often entails duplicating code
> from the initial implementation.
> # UDF implementors are exposed to the internals of Pig since they have to
> know when to return a tuple (Initial, Intermediate) and when not to (exec,
> Final).
> # The separation of Initial, Intermediate, and Final into separate classes
> forces code duplication and makes it hard for UDFs in other languages to use
> those interfaces.
> # There is unused code in the current interface that occasionally causes
> confusion (e.g. isAsynchronous)
> Any change must be done in a way that allows existing UDFs to continue
> working essentially forever.
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