Provide libraries with both synchronous and asynchronous access

[ya7010]

I am a library developer and am looking to support both sync and async.
(FromStrAsync, FromStr, etc...)

I thought it would be easy to create a sync version by creating an async API and tokio::executor::current_thread::block_on it.

But, if I call sync incorrectly in async runtime, I get an error with duplicate runtime startup.

Is there a way to make the compiler make an error in incorrect usage or is there a better way to implement this? Or block_on just to make an async implementation sync.

📝 Ideas for making sync and async implementations common include quansync in typescript. I am looking into whether a similar approach exists for Rust.

[Darksonn]

If you build a sync API by internally calling block_on on the async API, then you should not use the sync API from async code. Instead, just use the async version directly.

[ya7010]

Sorry for the late reply.

Yes, it should not be used.

What I am currently considering is to provide explicit API names such as from_str_sync, from_str_async.

However, I also think that overly explicit API names may be a bit redundant.

Ideally, I would consider the following

• Trying to run a synchronous version in an asynchronous process can result in a compile error
• Provide functions such as macros that detect whether it is asynchronous runtime and switch processing.

I would like to know if there is a better way for the developers of the library to inform users of the proper usage or hide it from them.

[Darksonn]

Unfortunately, Rust does not have any mechanism to prevent such mistakes at compile time.

[ya7010]

Thanks. This was helpful in the direction of my development.