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Minor typo fixes and a few wasm links added

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17
DESIGN.md
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@ -15,7 +15,7 @@ JS files.
Now unfortunately at the time of this writing the interface of wasm interop Now unfortunately at the time of this writing the interface of wasm interop
isn't very rich. Wasm modules can only call functions or export functions that isn't very rich. Wasm modules can only call functions or export functions that
deal exclusively with `u32`, `u64`, `f32`, and `f64`. Bummer! deal exclusively with `i32`, `i64`, `f32`, and `f64`. Bummer!
That's where this project comes in. The goal of `wasm-bindgen` is to enhance the That's where this project comes in. The goal of `wasm-bindgen` is to enhance the
"ABI" of wasm modules with richer types like classes, JS objects, Rust structs, "ABI" of wasm modules with richer types like classes, JS objects, Rust structs,
@ -103,7 +103,7 @@ Here we can see a few notable points of action:
from the stack. from the stack.
* Our exported function `foo`, takes an arbitrary argument, `arg0`, which is * Our exported function `foo`, takes an arbitrary argument, `arg0`, which is
converted to an index with the `addBorrowedObject` object function. The index converted to an index with the `addBorrowedObject` object function. The index
is the passed to wasm so wasm can operate with it. is then passed to wasm so wasm can operate with it.
* Finally, we have a `finally` which frees the stack slow as it's no longer in * Finally, we have a `finally` which frees the stack slow as it's no longer in
used, issuing a `pop` for what was pushed at the start of the function. used, issuing a `pop` for what was pushed at the start of the function.
@ -113,6 +113,7 @@ there! Let's take a look at the code that `wasm_bindgen!` generates in Rust:
```rust ```rust
// what the user wrote // what the user wrote
pub fn foo(a: &JsObject) { pub fn foo(a: &JsObject) {
// ...
} }
#[export_name = "foo"] #[export_name = "foo"]
@ -216,6 +217,7 @@ And finally, let's take a look at the Rust generated again too:
```rust ```rust
// what the user wrote // what the user wrote
pub fn foo(a: JsObject) { pub fn foo(a: JsObject) {
// ...
} }
#[export_name = "foo"] #[export_name = "foo"]
@ -341,9 +343,10 @@ happening:
and then we'll pass that ptr/length to wasm later on. and then we'll pass that ptr/length to wasm later on.
* Returning strings from wasm is a little tricky as we need to return a ptr/len * Returning strings from wasm is a little tricky as we need to return a ptr/len
pair, but wasm only supports one return value. To work around this we're pair, but wasm currently only supports one return value (multiple return values
actually returning a pointer to a ptr/len pair, and then using functions to [is being standardized](https://github.com/WebAssembly/design/issues/1146)).
access the various fields. To work around this in the meantime, we're actually returning a pointer to a
ptr/len pair, and then using functions to access the various fields.
* Some cleanup ends up happening in wasm. The `__wbindgen_boxed_str_free` * Some cleanup ends up happening in wasm. The `__wbindgen_boxed_str_free`
function is used to free the return value of `greet` after it's been decoded function is used to free the return value of `greet` after it's been decoded
@ -351,7 +354,7 @@ happening:
free the space we allocated to pass the string argument once the function call free the space we allocated to pass the string argument once the function call
is done. is done.
At this point it may be preditable, but let's take a look at the Rust side of At this point it may be predictable, but let's take a look at the Rust side of
things as well things as well
```rust ```rust
@ -465,7 +468,7 @@ returned pointer.
## Exporting a struct to JS ## Exporting a struct to JS
So far we've covered JS objects, importing functions, and exporting functions. So far we've covered JS objects, importing functions, and exporting functions.
This has given us quite a rich based to build on so far, and that's great! We This has given us quite a rich base to build on so far, and that's great! We
sometimes, though, want to go even further and define a JS `class` in Rust. Or sometimes, though, want to go even further and define a JS `class` in Rust. Or
in other words, we want to expose an object with methods from Rust to JS rather in other words, we want to expose an object with methods from Rust to JS rather
than just importing/exporting free functions. than just importing/exporting free functions.