[jira] [Created] (TINKERPOP3-896) Simplify the {{withSack}} methods of {{GraphTraversalSource}}.

["Marko A. Rodriguez (JIRA)" <ji...@apache.org>]

Marko A. Rodriguez created TINKERPOP3-896:
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             Summary: Simplify the {{withSack}} methods of {{GraphTraversalSource}}.
                 Key: TINKERPOP3-896
                 URL: https://issues.apache.org/jira/browse/TINKERPOP3-896
             Project: TinkerPop 3
          Issue Type: Improvement
          Components: process
    Affects Versions: 3.0.2-incubating
            Reporter: Marko A. Rodriguez
            Assignee: Marko A. Rodriguez
             Fix For: 3.1.0-incubating


We currently have these method:

{code}
withSack(initialValue,splitOperator,mergeOperator)
{code}

I messed this up. It should be:

{code}
withSack(splitOperator,mergeOperator)
{code}

Why? Because we use {{new Traverser()}} at other points in the code besides just with the {{TraverserGenerators}} (e.g. reducing barriers). Dah! The way this should be done is:

{code}
g.withSack(splitOperator,mergeOperator).V().sack(1.0)....
{code}

This way, the user defines the sack value at the traversal level, not at the construction level and thus, any other constructions of a traverser don't have a sack value.

The other option is to simply say: 
  "Make sure your initial sack value is the identity in the set (given the merge operator)"

Where you will do:

{code}
g.withSack(0,sum).V().sack(1).blah.blah
{code}

This ensures that EVERY traverser in the computation has a sack value, but that if a traverser is created later in computation, its sack value is the identity. With that, we should change the term "initial value" to "identity value" so people understand the consequence of the logic.



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