Ok now I understand why you did that.
The problem is that you can't use the type parameters `E` from your
GraphTraversal because you split up `group` and `by` into separate steps.
E.g. for `g.V()` the type parameter `E` is `Vertex`, which makes sense.
But for `g.V().group()` the type parameter `E` becomes `Map<Vertex,
???>`. So then the by step doesn't know that it operates on a Vertex any
more and you have to pass `Vertex` to the `by` function.
I.e. the developer has to specify all types rather than letting the
compiler figure it out - e.g. in GroupTest.java:302 you had to write out
the types all the way:
`g.V().<String, Long>group().<Vertex>by(v -> v.<String>value("name"))`
If you would have kept the groupBy step, the above would then become
much shorter:
`g.V().groupBy(v -> v.<String>value("name"))`
Basically, the split of `group` and `by` makes the java API painful.
Groovy doesn't care about the types so you probably didn't notice. If we
care about the java API (I certainly do), then I would suggest to go
back to `groupBy`, `orderBy` etc. or come up with an alternative solution.
Does this make sense?
On 01/12/2016 04:51 AM, Marko Rodriguez wrote:
Hi,
I'm not sure why I did this. I suspect it could just be <U,V>. If you type it
like that, do you run into an compilation issues? If you get it working as such and
it makes sense without having to change any of the casts in the test suites, please
provide a PR.
Thanks,
Marko.
http://markorodriguez.com
On Jan 10, 2016, at 3:51 PM, Michael Pollmeier <[email protected]>
wrote:
No answer on this one yet - what's a better place to ask? Should I create a
jira ticket instead?
On 12/21/2015 06:59 PM, Michael Pollmeier wrote:
I don't understand the types on the `by` steps that take a function
projection.
1) Shouldn't it be `Function<E, V>` for the function parameter in both
cases?
2) What is the reason for constraining the function passed to the second
one to `Element`?
without comparator:
<V> GraphTraversal<S, E> by(Function<V, Object>)
with comparator:
<V> GraphTraversal<S, E> by(Function<Element, V>, Comparator<V>)
(from GraphTraversal.java)
Cheers
Michael
