[jira] [Commented] (PIG-1998) Allow macro to return void

["Richard Ding (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/PIG-1998?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13022393#comment-13022393 ] 

Richard Ding commented on PIG-1998:
-----------------------------------

Patch-test results:

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     [exec] -1 overall.  
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     [exec]     +1 @author.  The patch does not contain any @author tags.
     [exec] 
     [exec]     +1 tests included.  The patch appears to include 5 new or modified tests.
     [exec] 
     [exec]     +1 javadoc.  The javadoc tool did not generate any warning messages.
     [exec] 
     [exec]     -1 javac.  The applied patch generated 952 javac compiler warnings (more than the trunk's current 948 warnings).
     [exec] 
     [exec]     +1 findbugs.  The patch does not introduce any new Findbugs warnings.
     [exec] 
     [exec]     +1 release audit.  The applied patch does not increase the total number of release audit warnings.
{code}

> Allow macro to return void
> --------------------------
>
>                 Key: PIG-1998
>                 URL: https://issues.apache.org/jira/browse/PIG-1998
>             Project: Pig
>          Issue Type: Improvement
>          Components: impl
>    Affects Versions: 0.9.0
>            Reporter: Richard Ding
>            Assignee: Richard Ding
>             Fix For: 0.9.0
>
>         Attachments: PIG-1998_1.patch
>
>
> Pig macro is allowed to not have output alias. But this property isn't clear from macro definition and macro invocation (macro inline). Here we propose to make it clear:
> 1. If a macro doesn't output any alias, it must specify void as return value. For example:
> {code}  
> define mymacro(...) returns void {
>    ... ...
> };
> {code}
> 2. If a macro doesn't output any alias, it must be invoked without return value. For example, to invoke above macro, just specify:
> {code}
> mymacro(...);
> {code}
> 3. Any non-void return alias in the macro definition must exist in the macro body and be prefixed with $. For example:
> {code}  
> define mymacro(...) returns B {
>    ... ...
>    $B = filter ...;
> };
> {code}

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