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https://issues.apache.org/jira/browse/GIRAPH-221?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13403183#comment-13403183
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Alessandro Presta commented on GIRAPH-221:
------------------------------------------
I'm not trying to eliminate the for-each, on the contrary I want to make it
more explicit what we're iterating on, so that we stop using the .iterator()
version instead.
What I'm unsure about is whether we should ask concrete vertex classes to
implement outEdgesIterator() or directly outEdges().
As for BasicVertex being an Iterable: I don't see a Vertex as a Collection of
edges, considering there's much more to it (most notably a value). I think the
form {code:java} for (I edge : this){code} illustrates this well. I think a
Vertex *has-a* Collection of edges.
The Pregel API, for example, includes {code:java}OutEdgeIterator
GetOutEdgeIterator(){code}
Not a big deal in the end, just trying to find the most intuitive API.
> Make iteration over edges more explicit
> ---------------------------------------
>
> Key: GIRAPH-221
> URL: https://issues.apache.org/jira/browse/GIRAPH-221
> Project: Giraph
> Issue Type: Improvement
> Components: graph
> Reporter: Alessandro Presta
> Assignee: Alessandro Presta
> Priority: Minor
>
> Is there any particular reason why BasicVertex implements Iterable?
> It seems to me that doing
> {code:java}
> for (I neighbor : vertex)
> {code}
> is not that explicit, and
> {code:java}
> for (I neighbor : this)
> {code}
> gets even obscure (which may be why all examples in the codebase explicitly
> instantiate an iterator and call next()).
> What I propose is a more explicit
> {code:java}
> Iterator<I> outEdgesIterator()
> {code}
> and also a convenient
> {code:java}
> Iterable<I> outEdges()
> {code}
> so, for example, an algorithm can use
> {code:java}
> for (IntWritable neighbor : outEdges())
> {code}
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