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https://issues.apache.org/jira/browse/TINKERPOP-1901?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16394475#comment-16394475
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ASF GitHub Bot commented on TINKERPOP-1901:
-------------------------------------------
GitHub user FlorianHockmann opened a pull request:
https://github.com/apache/tinkerpop/pull/815
TINKERPOP-1901 Transform enums into classes in Gremlin.Net
https://issues.apache.org/jira/browse/TINKERPOP-1901
The various Gremlin tokens like `T`, `Order`, and so on are now classes in
Gremlin.Net so they can implement interfaces which makes them usable in more
steps.
Using the example from the issue description, the Java step
```java
public default <V> GraphTraversal<S, E> by(final Traversal<?, ?> traversal,
final Comparator<V> comparator)
```
now has this equivalent in Gremlin.Net:
```cs
public GraphTraversal<S, E> By (ITraversal traversal, IComparator
comparator)
```
and `Order` implements `IComparator`.
This example already shows that the Gremlin.Net versions of those
**interfaces aren't generic** which means in practice that they can still be
used in some places where it shouldn't be possible. Especially `T` implements
`Function<Element, Object>` in Java, but simply `IFunction` in Gremlin.Net. So
users can still use `T` for steps that don't take a lambda with an `Element`
argument. However, this was also possible before as we simply had the `object`
type in those places before this PR. So I'd say that we tackle that one later.
All tests pass with `docker/build.sh -t -i -d`
VOTE +1
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/apache/tinkerpop TINKERPOP-1901
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/tinkerpop/pull/815.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #815
----
commit dcf3da3917a9626d432ef26089bb05c6a15158ed
Author: Florian Hockmann <fh@...>
Date: 2018-03-10T18:17:15Z
TINKERPOP-1901 Transformed Gremlin.Net enums into classes
commit d012171e97d5d87108eef3d0257a8b859f77de04
Author: Florian Hockmann <fh@...>
Date: 2018-03-10T18:21:46Z
TINKERPOP-1901 Add interfaces for tokens in Gremlin.Net
These interfaces simply represent their Java counterparts which allows
to use them as arguments in Gremlin steps.
----
> Enable usage of enums in more steps in Gremlin.Net
> --------------------------------------------------
>
> Key: TINKERPOP-1901
> URL: https://issues.apache.org/jira/browse/TINKERPOP-1901
> Project: TinkerPop
> Issue Type: Improvement
> Components: dotnet
> Affects Versions: 3.2.7, 3.3.1
> Reporter: Florian Hockmann
> Assignee: Florian Hockmann
> Priority: Minor
> Fix For: 3.2.8, 3.3.2
>
>
> Java enums can implement interfaces and some Gremlin steps take interfaces as
> arguments that are implemented by enums like {{T}} or {{P}} in Java. However,
> C# enums can't have any methods and therefore also not implement interfaces.
> For this reason, step arguments whose type is one of those interfaces
> ({{Predicate}}, {{Function}}, ...) currently have the type {{object}} in
> Gremlin.Net which makes it hard for users to know what kind of values they
> can use for these arguments.
> This overload of the {{By}} step is a good example for this:
> * In Gremlin-java:
> {code:java}
> public default <V> GraphTraversal<S, E> by(final Traversal<?, ?> traversal,
> final Comparator<V> comparator)
> {code}
> * In Gremlin.Net:
> {code}
> public GraphTraversal<S, E> By (object function, object comparator)
> {code}
> [~jorgebg] [suggested two possible
> solutions|https://github.com/apache/tinkerpop/pull/792#discussion_r167847541]
> for this problem:
> {quote} * Use a class for T (not an enum), properties like T.Id could return
> instances of whatever interface we create for it. Given that java enums
> functionality is more comprehensive than what C# currently supports, it makes
> sense to use a class IMO.
> * Generate the offending traversal methods manually.{quote}
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