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https://issues.apache.org/jira/browse/PIG-1510?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12890899#action_12890899
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Swati Jain commented on PIG-1510:
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I just attached my patch, please see if it is significantly different from what
you are planning to add and let me know if it is so I can redesign if required.
Also, if this is the same as what you did, and If it helps your work, I could
add this as a separate change.
> Add `deepCopy` for LogicalExpressions
> -------------------------------------
>
> Key: PIG-1510
> URL: https://issues.apache.org/jira/browse/PIG-1510
> Project: Pig
> Issue Type: New Feature
> Components: data
> Affects Versions: 0.8.0
> Reporter: Swati Jain
> Assignee: Swati Jain
> Fix For: 0.8.0
>
> Attachments: deepCopy.patch
>
>
> It would be useful to have a way to `deepCopy` an expression. `deepCopy` will
> create a new object so that changes made to one object will not reflect in
> the copy. There are 2 reasons why we don't override clone.
> * It may be better to use `deepCopy` since the copy semantics are explicit
> (since deepCopy may be expensive).
> * A second important reason for defining `deepCopy` as a separate routine is
> that it can be passed a plan as an argument which will be updated as the
> expression is copied (through plan.add and plan.connect).
> The usage would look like the following:
> {noformat}
> LogicalExpressionPlan logicalPlan = new LogicalExpressionPlan();
> LogicalExpression copyExpression = origExpression.deepCopy( logicalPlan );
> {noformat}
> An immediate motivation for this would be for constructing the expressions
> that constitute the CNF form of an expression.
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