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https://issues.apache.org/jira/browse/TINKERPOP-1854?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16362211#comment-16362211
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ASF GitHub Bot commented on TINKERPOP-1854:
-------------------------------------------
Github user jorgebay commented on a diff in the pull request:
https://github.com/apache/tinkerpop/pull/792#discussion_r167847541
--- Diff: gremlin-dotnet/glv/generate.groovy ---
@@ -48,7 +48,7 @@ def toCSharpTypeMap = ["Long": "long",
"TraversalMetrics": "E2",
"Traversal": "ITraversal",
"Traversal[]": "ITraversal[]",
- "Predicate": "TraversalPredicate",
+ "Predicate": "object",
--- End diff --
Sorry, I've read it a while back when the pull request was first opened and
forgot about it :/
There are several consequences of using an untyped API for those methods:
- We are stuck maintaining an API for which we can't predict how its being
used (specially considering that db providers might support additional
functionality on top of the GLV).
- The user looses compile time checks.
- It will be hard for the user to find the correct expected type (`Lambda`)
and the error message on serialization might be unclear.
I think we should avoid using `object` for predicates.
We could use different workarounds for the `T` issue you highlighted above:
- 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.
> Support lambdas in Gremlin.Net
> ------------------------------
>
> Key: TINKERPOP-1854
> URL: https://issues.apache.org/jira/browse/TINKERPOP-1854
> Project: TinkerPop
> Issue Type: Improvement
> Components: dotnet
> Affects Versions: 3.3.0, 3.2.6
> Reporter: Florian Hockmann
> Assignee: Florian Hockmann
> Priority: Major
>
> Gremlin.Net should support lambdas. We already discussed this in [the pull
> request for TINKERPOP-1752|https://github.com/apache/tinkerpop/pull/712].
> Here is what [~spmallette] said over there:
> {quote}
> Any reason we don't support lambdas? Even if .NET can't support them natively
> for some reason wouldn't we minimally support the ability to pass a
> python/groovy/etc lambda? it's kinda weird that way, but i think back to the
> point that kuppitz made on the dev list the other day where he stated that he
> doesn't always find a way out of using lambdas in production systems he works
> on - so ultimately users will need that kind of capability i think.
> {quote}
> C# lambdas would require some kind of C# parser on the server side, so at
> least in the beginning a way to send lambdas from already supported languages
> in Gremlin.Net should be enough.
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