Derive Clone for the builders in object-store.

[winding-lines]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

I am using the object-store create in polars. The async code is generally contained in a small number of functions. I plan to pass around builders (eg AmazonS3Builder, MicrosoftAzureBuilder, GoogleCloudStorageBuilder) and instantiate an object-store based on the urls that are being passed in. I cannot currently use one builder more than one since they don't implement Clone.

Is there a reason why these structs are not implementing Clone?

Describe the solution you'd like

Implement (most likely derive) Clone for AmazonS3Builder, MicrosoftAzureBuilder, GoogleCloudStorageBuilder and other object_store builders.

Describe alternatives you've considered

I can recreate the struct from their fields but then I will need to maintain the code on my side.

Additional context

[alamb]

I do not think there is any reason these structs can't implement clone. We would welcome a contribution to do so.

[winding-lines]

@alamb unfortunately the Builders contain Result and Error fields which are not clonable and there is no easy way to make them clonable.

One option that I see is do a slight refactoring of the code where the data from the user is saved in a separate Config object, before any fallible processing is done. Then we can clone that part.

Note that delta-rs is also going through some hoops here: https://github.com/delta-io/delta-rs/tree/main/rust/src/builder

Let me know what you think.

[tustvold]

unfortunately the Builders contain Result and Error fields which are not clonable and there is no easy way to make them clonable.

This is a relatively recent change, added in #3327, and not yet released. We could tweak the implementation of this slightly to make this simpler. I'll have a play

[winding-lines]

Thanks @tustvold!

[winding-lines]

@alamb and @tustvold Happy New Year 2023!

I tested @tustvold 's branch inside my polars PR and what would help me tremendously is an extension of this issue. In addition to Clone it would be super helpful to also derive serde::Serializer and serde::Deserializer. I tested this on @tustvold 's branch and it just works on top of the existing cleanup. This affects the 3 builders an 2 transitively used struct.

Would it be ok to increase the scope? Many thanks!

[alamb]

I think adding Serialize and Deserialize would be just fine, though perhaps we could do it as a follow on PR?

I think it would simply require adding

#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]

To each of the builders