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https://issues.apache.org/jira/browse/PIG-969?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12994447#comment-12994447
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Dmitriy V. Ryaboy commented on PIG-969:
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Why do you say that there isn't a valid reason to provide arguments in the
DEFINEd constructor?
Seems needlessly limiting to disallow constructor arguments when
getArgToFuncMapping is defined. getArgToFuncMapping is not static, so it can
pass on the parameters the constructor was called with to any FuncSpecs it
returns, giving us option 3 that just requires documentation changes. Unless I
am missing something?
> Default constructor of UDF gets called for UDF with parameterised constructor
> , if the udf has a getArgToFuncMapping function defined
> -------------------------------------------------------------------------------------------------------------------------------------
>
> Key: PIG-969
> URL: https://issues.apache.org/jira/browse/PIG-969
> Project: Pig
> Issue Type: Bug
> Components: impl
> Reporter: Thejas M Nair
> Assignee: Thejas M Nair
> Fix For: 0.9.0
>
>
> This issue is discussed in
> http://www.mail-archive.com/[email protected]/msg00524.html . I am
> able to reproduce the issue. While it is easy to fix the udf, it can take a
> lot of time to figure out the problem (until they find this email
> conversation!).
> The root cause is that when getArgToFuncMapping is defined in the udf , the
> FuncSpec returned by the method replaces one set by define statement . The
> constructor arguments get lost. We can handle this in following ways -
> 1. Preserve the constructor arguments, and use it with the class name of the
> matching FuncSpec from getArgToFuncMapping .
> 2. Give an error if constructor paramerters are given for a udf which has
> FuncSpecs returned from getArgToFuncMapping .
> The problem with approach 1 is that we are letting the user define the
> FuncSpec , so user could have defined a FuncSpec with constructor (though
> they don't have a valid reason to do so.). It is also possible the the
> constructor of the different class that matched might not support same
> constructor parameters. The use of this function outside builtin udfs are
> also probably not common.
> With option 2, we are telling the user that this is not a supported use case,
> and user can easily change the udf to fix the issue, or use the udf which
> would have matched given parameters (which unlikely to have the
> getArgToFuncMapping method defined).
> I am proposing that we go with option 2 .
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