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https://issues.apache.org/jira/browse/PIG-158?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12586491#action_12586491
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Shravan Matthur Narayanamurthy commented on PIG-158:
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Somehow, I think I am missing the point. I still don't see the difference
between instantiating a new visitor because all we still have is access to w
and currentWalker in this design and the same is available in the other design
where we have the current visitor and the newly instantiated visitor. The
difference I see is that the traversal logic is separated out of the visitor as
a walker and composed into the visitor, which seems to be the right thing to
do. Other than that I don't see any difference. I must be missing something.
In the old design, we would do something like this in the LOVisitor for filter:
public void visit(LOFilter f)
{
ExprPlanVisitor epv = new ExprPlanVisitor(f.getExprPlan());
epv.visit();
}
Even here, we have access to epv and the current visitor. Can someone please
tell me what can't be done in this case that can be in the visitor/walker?
> Rework logical plan
> -------------------
>
> Key: PIG-158
> URL: https://issues.apache.org/jira/browse/PIG-158
> Project: Pig
> Issue Type: Sub-task
> Components: impl
> Reporter: Alan Gates
> Assignee: Alan Gates
> Attachments: logical_operators.patch, logical_operators_rev_1.patch,
> logical_operators_rev_2.patch, logical_operators_rev_3.patch,
> visitorWalker.patch
>
>
> Rework the logical plan in line with
> http://wiki.apache.org/pig/PigExecutionModel
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