grtlr opened a new issue, #8033: URL: https://github.com/apache/arrow-rs/issues/8033
**Which part is this question about** The `arrow-rs` library. **Describe your question** I'm currently working on a tool that converts `protobuf` messages into Arrow data. To capture the nested structure of `protobuf` messages, I'm using type-erased `Box<dyn ArrayBuilder>`s. While doing so, I stumbled upon the fact that [`UnionBuilder`](https://docs.rs/arrow/latest/arrow/array/struct.UnionBuilder.html) does not implement the [`ArrayBuilder`](https://docs.rs/arrow/latest/arrow/array/trait.ArrayBuilder.html) trait. Is there a technical limitation for this? If not, I could try to come up with an implementation. **Additional context** To implement this, I would add `Send + Sync` to the `FieldDataValues` trait. Then it looks like it's enough to implement `finish` and `finish_cloned`, which I could implement similar to `UnionBuilder::build()`. Would it be ok to `panic` if the underlying `UnionArray::try_new` fails? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: github-unsubscr...@arrow.apache.org.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
