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https://issues.apache.org/jira/browse/GIRAPH-221?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13403774#comment-13403774
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Jake Mannix commented on GIRAPH-221:
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@Eli, ok, I can see the fact that it's hard to figure out which method to call,
making it explicit is better.
@Alessandro: we used to iterate over Edge<I, E>, but we got rid of it because
there are some very memory-efficient constructs (where E,I,V,M are all
primitives) where instantiating extra objects is wasteful (even knowing that
Iterator<Long> will involve boxing the long -> Long). I'd have to look over
the discussions, but I think we started discouraging the use of the Edge<I, E>
class in usercode at all, as E is the edge type, and I is the target vertex
type, and all you really need is a way to look up one w.r.t. the other in a
well-documented method. Since having E be null sometimes is allowed, better to
iterate over I and fetch E than the reverse.
So on further consideration, forget syntactic sugar, IMO it's fine to do just
do for(Iterator<I> it = v.outEdgeIterator(); it.hasNext();) { I i = it.next();
... }
> 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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