b9dc38f4e1
This commit removes the need to use `HostRef<Engine>` in the Rust API. Usage is retained in the C API in one location, but otherwise `Engine` can always be used directly. This is the first step of progress on #708 for the `Engine` type. Changes here include: * `Engine` is now `Clone`, and is documented as being cheap. It's not intended that cloning an engine creates a deep copy. * `Engine` is now both `Send` and `Sync`, and asserted to be so. * Usage of `Engine` in APIs no longer requires or uses `HostRef`.
wasmtime-rust - Using WebAssembly from Rust
This crate is intended to be an example of how to load WebAssembly files from a
native Rust application. You can always use wasmtime and its family of crates
directly, but the purpose of this crate is to provide an ergonomic macro:
#[wasmtime_rust::wasmtime]
trait WasmMarkdown {
fn render(&mut self, input: &str) -> String;
}
fn main() -> anyhow::Result<()> {
let mut markdown = WasmMarkdown::load_file("markdown.wasm")?;
println!("{}", markdown.render("# Hello, Rust!"));
Ok(())
}
The wasmtime macro defined in the wasmtime-rust crate is placed on a trait
which includes the set of functionality which a wasm module should export. In
this case we're expecting one render function which takes and returns a
string.
The macro expands to a struct with all of the methods on the trait (they must
all be &mut self) and one function called load_file to actually instantiate
the module.
Note that this macro is still in early stages of development, so error messages aren't great yet and all functionality isn't supported yet.
Missing features
Currently if the wasm module imports any symbols outside of the WASI namespace the module will not load. It's intended that support for this will be added soon though!