add Resource::take method to wit_bindgen::rt
#753
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This allows the guest to take back ownership of an exported resource from the host; you can think of it as the reverse of `Resource::new`. It's a bit awkward to do this for the time being; WebAssembly/component-model#238 will improve the situation if accepted. Signed-off-by: Joel Dice <[email protected]>
crates/guest-rust/src/lib.rs
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| /// Takes back ownership of the object, dropping the resource handle. | ||
| pub fn take(resource: Self) -> T |
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Could this be rename to into_inner perhaps? The take terminology seems derivitive of Option<T> which is ideally only an implementation detail here.
crates/guest-rust/src/lib.rs
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| @@ -250,7 +250,18 @@ impl<T: WasmResource> Resource<T> { | |||
| where | |||
| T: RustResource, | |||
| { | |||
| let _ = Box::from_raw(rep as *mut T); | |||
| let _ = Box::from_raw(rep as *mut Option<T>); | |||
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Would you be up for a small refactoring of this module? If so I think it'd be good to have something like
type RawRep<T> = Option<T>;or something like that where all of these casts and various "raw" methods would work with RawRep<T>. That way future changes to RawRep<T> would help trigger compilation errors where appropriate. Basically I think it'd be good to centralize the representation of Option<T> if possible.
crates/rust/src/bindgen.rs
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| @@ -443,7 +443,7 @@ impl Bindgen for FunctionBindgen<'_, '_> { | |||
| .as_deref() | |||
| .unwrap() | |||
| .to_upper_camel_case(); | |||
| format!("&*({op} as u32 as usize as *const {name})") | |||
| format!("Option::as_ref(&*({op} as u32 as usize as *const Option<{name}>)).unwrap()") | |||
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Mind adding a helper method to Resource<T> which is #[doc(hidden)] to call here? That way this could avoid duplicating knowledge of the internal representation across the code generator and the actual source
- add `type RawRep<T> = Option<T>` alias - rename `Resource::take` to `Resource::into_inner` - add `Resource::lift_borrow` and use it in code generator Signed-off-by: Joel Dice <[email protected]>
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@alexcrichton thanks for the feedback; I just pushed and update. I wasn't sure about the scope of your |
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This allows the guest to take back ownership of an exported resource from the host; you can think of it as the reverse of
Resource::new. It's a bit awkward to do this for the time being;WebAssembly/component-model#238 will improve the situation if accepted.