Use shorter lifetimes

[alexkreidler]

Right now, I use the function: fn nurse( &self, fut: impl Future<Output = Out> + Send + 'static ) -> Result<(), NurseErr>; This unfortunately means I can't use references in my async fn with a lifetime less than 'static, which is quite inconvenient.

I'm not really sure of the complexity of changing that, but I'd appreciate any thoughts you have on it.

[najamelan]

You can't spawn non static futures on any executor without unsafe. The problem is that you can use std::mem::forget to leak the nursery, which would then outlive it's parent scope, which might hold the pointed to value. Thus when the stack frame ends, that value get's dropped, but the nursery can outlive it and still run code that has a reference to that memory. That is a memory safety issue which is not allowed in safe rust.

The only crate that can help you here is https://docs.rs/async-scoped which requires you use unsafe. If you want to go that path, I would suggest you use async-scoped. Unless there is some very good arguments for it and it can be implemented cleanly, I don't have any plans to add such an unsafe API to async_nursery. That being said, if you have some very compelling argument, please share.

Some more discussion about the issue can be found here: tokio-rs/tokio#1879 (comment)

[najamelan]

ps: I'm adding this to the readme: 6c2620e#diff-04c6e90faac2675aa89e2176d2eec7d8R69

ps2: If you are struggling to design something, don't hesitate to ask. Maybe there's a better way to achieve what you want.

[alexkreidler]

Thanks!