[ARROW-10390] [Rust] [Parquet] Regression Can not implement custom ParquetWriter because `TryClone` is not publically exported

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.0
• Fix Version/s: 3.0.0
• Component/s: Rust
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/18339
• Assignee: Andrew Lamb
• Reporter: Andrew Lamb
• Created: 26/Oct/20 14:31
• Updated: 11/Jan/23 08:13
• Resolved: 26/Oct/20 20:53

Description

As of this commit

https://github.com/apache/arrow/commit/7155cd5488310c15d864428252ca71dd9ebd3b48

I don't think it is possible for a user of the arrow trait to implement a custom Parquet writer anymore. Specifically, theParquetWriter trait requires `TryClone` implemented, https://github.com/apache/arrow/blob/master/rust/parquet/src/file/writer.rs#L117-L118

pub trait ParquetWriter: Write + Seek + TryClone {}
impl<T: Write + Seek + TryClone> ParquetWriter for T {}

/// A serialized implementation for Parquet [`FileWriter`].
/// See documentation on file writer for more information.
pub struct SerializedFileWriter<W: ParquetWriter> {

but `TryClone` is can not be used. It is a `pub` trait:

https://github.com/apache/arrow/blob/master/rust/parquet/src/util/io.rs#L28-L32

/// TryClone tries to clone the type and should maintain the `Seek` position of the given
/// instance.
pub trait TryClone: Sized {
    /// Clones the type returning a new instance or an error if it's not possible
    /// to clone it.
    fn try_clone(&self) -> Result<Self>;
}

But the module it is (util.io) in is not marked as `pub`: https://github.com/apache/arrow/blob/master/rust/parquet/src/lib.rs#L39

```
#[macro_use]
mod util;
#[cfg(any(feature = "arrow", test))]
pub mod arrow;
pub mod column;
pub mod compression;
mod encodings;
pub mod file;
pub mod record;
pub mod schema;

Issue Links

• links to: GitHub Pull Request #8528