[jira] [Created] (TINKERPOP-1670) End type lost when using promise()

["Andy Tolbert (JIRA)" <ji...@apache.org>]

Andy Tolbert created TINKERPOP-1670:
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             Summary: End type lost when using promise()
                 Key: TINKERPOP-1670
                 URL: https://issues.apache.org/jira/browse/TINKERPOP-1670
             Project: TinkerPop
          Issue Type: Bug
    Affects Versions: 3.2.4
            Reporter: Andy Tolbert


The {{Traversal.promise}} method loses type information when used so the type of the returned future is not as complete as it could be.

For example:

{code:java}
g.V().hasLabel("person").has("name", "marko").promise(Traversal::next);
{code}

Returns a {{CompletableFuture<Object>}} instead of {{CompletableFuture<Vertex>}}.

{code:java}
g.V().hasLabel("person").promise(Traversal::toList);
{code}

Returns a {{CompletableFuture<List>}} instead of {{CompletableFuture<List<Vertex>}}.

The fix for this could be as simple as adding the start and end (S,E) types to the traversal that is the input of the function:

{code:java}
public default <T> CompletableFuture<T> promise(final Function<Traversal, T> traversalFunction)
{code}

to:

{code:java}
public default <T> CompletableFuture<T> promise(final Function<Traversal<S,E>, T> traversalFunction)
{code}

Need to test this a bit more though, but I think that should work.



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