Struct MaybeAsync 

pub struct MaybeAsync<T> { /* private fields */ }

Represents a result that may be computed synchronously or asynchronously by user code.

Rust does not currently allow async fn in trait methods, so we need a workaround. There are crates such as async_trait which provide proc_macros that do this, but they don’t provide an optimization to avoid the heap allocation if the underlying implementation is synchronous.

This allows us to use async operations in Rust if desired, but just have synchronous callbacks in the FFI without paying always allocating.

Implementations

impl<T> MaybeAsync<T>

pub async fn get(self) -> T

Retrieve the value, which might be available immediately or require awaiting

pub fn ready(result: T) -> Self

Construct a new MaybeAsync from an already available result

pub fn asynchronous<F>(result: F) -> Self

where F: Future<Output = T> + Send + 'static,

Construct a new MaybeAsync from a future which yields the value eventually