Writing examples that run natively and on WASM

help
1

I'm working on a sound library. This library shall be used as native compilation and as WASM running in a browser.

I provided an example (runnable with cargo run --example=name) which works fine.
Is there a way to modify that example to work in an WASM environment as well?

When targeting WASM the required packages are completely different and I don't know how to integrate that in my Cargo.toml (see cpal/Cargo.toml at master · RustAudio/cpal · GitHub for an example)
Where would I have to place the html and js files for those examples?

If there's no (easy) solution I'll fall back to using some dedicated example crates.

2

Here is one option that allows a feature to gate the dependencies

[features]
wasm = ["cpal/wasm-bindgen", "wasm-bindgen", "wee_alloc", "web-sys" ]

[dependencies]
cpal = { path = "../.." }
wasm-bindgen = { version = "0.2.45", optional = true }
wee_alloc = { version = "0.4.2", optional = true }

[dependencies.web-sys]
version = "0.3.22"
features = ["console"]
optional = true
3

Thank you, but where do I have to place that to make it work for example code only?
I don't want to add those dependencies to my main crate.

4

If you can live with users running:

cargo run --package <example_name>

instead of

cargo run --example <example_name>

Then what you can do is:

  • Put all examples separate $repository/examples/example_name/ directories

  • Each example has its own Cargo.toml as though it's a regular crate

  • Declare the top level crate as a workspace, and include the examples as members:

    # Cargo.toml
[workspace]
members = ["examples/*"]

I've got a project that does this -- examples run natively with non-wasm dependencies, and on WASM with those dependencies, and the wasm dependencies aren't part of the library.

Repository: GitHub - azriel91/nginee: Experimental async game engine.
Example: https://nginee.rs/examples/event_loop_console.html

1 Like
5

Thanks, that project is already part of a workspace. I could add those examples as prefixed package. Like "example-beep". That could be a useful work-around.

6

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