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https://issues.apache.org/jira/browse/PIG-3198?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jonathan Coveney updated PIG-3198:
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Attachment: PIG-3198-0.patch
So I actually implemented this. You can check TestBuilinInvoker for some
examples, but generally the syntax is as such:
{code}
a = foreach @ generate invoke(x)concat(x);
{code}
in the case of a function on another type and
{code}
a = foreach @ generate invoke&Integer.valueOf(x);
{code}
in the case of static types.
Currently it should support any function taking 0+ PigType arguments and
returning a PigType argument...in the future we could allow people to cast
Object, or to chain together non-PigTypes but that was a bit out of the scope
of what I wanted to work on for this.
I actually don't love the syntax and would love to evolve it, but that portion
of the parser is really hairy and it is really difficult not to introduce
ambiguities...after about 10 hours of banging my head on it I went with the
above. I'd love to have some eyes on this for technical merit etc.
Essentially, this turns any PigType->PigType method into a UDF without having
to have a builtin, which I think is cool. This means people can have an
arbitrary method on their classpath and don't have to go through the annoyance
of wrapping it in a UDF. Ideally this cuts down on the number of lame builtin
functions we need to add as people can just use this (it uses bytecode
generation so is as performant as any code we'd write, though there are a
couple of bytecode optimizations I could do down the line).
> Let users use any function from PigType -> PigType as if it were builtlin
> -------------------------------------------------------------------------
>
> Key: PIG-3198
> URL: https://issues.apache.org/jira/browse/PIG-3198
> Project: Pig
> Issue Type: Bug
> Reporter: Jonathan Coveney
> Fix For: 0.12
>
> Attachments: PIG-3198-0.patch
>
>
> This idea is an extension of PIG-2643. Ideally, someone should be able to
> call any function currently registered in Pig as if it were builtin.
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