Initial support for closures #101
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fitzgen
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fitzgen
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This looks great!
Only nitpick is that it would be great to have somewhere where the overall strategy, and how the pieces fit together, is documented.
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OwnershipKind? When I saw TypeKind I was expecting something like scalar vs struct vs enum vs function...
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Already this PR is simply the bare-bones of supporting closures, it only supports stack closures being passed to imported functions (aka Rust closures passed to JS) whose arguments are only numbers. There's three other features I'd ideally like to support long-term
The last two are unfortunately stalled as I can't figure out a way to do them right now, but the first one I'm hoping to attach to this PR before landing |
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Ok! I've pushed up some more ambitious changes which support long-lived @fitzgen mind giving this another look? I'm specifically curious for your take on |
This commit starts wasm-bindgen down the path of supporting closures. We discussed this at the recent Rust All-Hands but I ended up needing to pretty significantly scale back the ambitions of what closures are supported. This commit is just the initial support and provides only a small amount of support but will hopefully provide a good basis for future implementations. Specifically this commit adds support for passing `&Fn(...)` to an *imported function*, but nothing elese. The `&Fn` type can have any lifetime and the JS object is invalidated as soon as the import returns. The arguments and return value of `Fn` must currently implement the `WasmAbi` trait, aka they can't require any conversions like strings/types/etc. I'd like to soon expand this to `&mut FnMut` as well as `'static` closures that can be passed around for a long time in JS, but for now I'm putting that off until later. I'm not currently sure how to implement richer argument types, but hopefully that can be figured out at some point!
Docs coming soon!
As soon as we've removed unneeded exports immediately run a gc pass to ensure that we don't bind functions in JS that don't actually end up getting needed.
This commit starts wasm-bindgen down the path of supporting closures. We
discussed this at the recent Rust All-Hands but I ended up needing to pretty
significantly scale back the ambitions of what closures are supported. This
commit is just the initial support and provides only a small amount of support
but will hopefully provide a good basis for future implementations.
Specifically this commit adds support for passing
&Fn(...)to an importedfunction, but nothing elese. The
&Fntype can have any lifetime and the JSobject is invalidated as soon as the import returns. The arguments and return
value of
Fnmust currently implement theWasmAbitrait, aka they can'trequire any conversions like strings/types/etc.
I'd like to soon expand this to
&mut FnMutas well as'staticclosures thatcan be passed around for a long time in JS, but for now I'm putting that off
until later. I'm not currently sure how to implement richer argument types, but
hopefully that can be figured out at some point!