valence/CONTRIBUTING.md

Valence has a public Discord server here and GitHub discussions here. Check those out if you have additional questions or comments.

What version of Rust should I use?

To use Valence, only the most recent stable version of Rust is required. However, contributors should know that unstable rustfmt settings are enabled in the project. To run rustfmt with the nightly toolchain, use the cargo +nightly fmt command.

What issues should I work on?

Issues labelled good first issue are a good place to start. This label is reserved for issues that are relatively uncontroversial and shouldn't require too much specialized domain knowledge to complete. New contributors are not required to start with these issues.

If you plan to work on something that's not an open issue, consider making one first so that it can be discussed. This way, your contribution will not be rejected when it is submitted for review.

Playgrounds

Playgrounds are meant to provide a quick and minimal environment to test out new code or reproduce bugs. Playgrounds are also a great way test out quick ideas. This is the preferred method for providing code samples in issues and pull requests.

To get started with a new playground, copy the template to playground.rs.

cp tools/playground/src/playground.template.rs tools/playground/src/playground.rs

Make your changes to crates/playground/src/playground.rs. To run it:

cargo run -p playground # simply run the playground, or
cargo watch -c -x "run -p playground" # run the playground and watch for changes

Automatic Checks

When you submit a pull request, your code will automatically run through clippy, rustfmt, etc. to check for any errors. If an error does occur, it must be fixed before the pull request can be merged.

Code Conventions

Here are some rules you should follow for your code. Generally the goal here is to be consistent with existing code, the standard library, and the Rust ecosystem as a whole. Nonconforming code is not necessarily a blocker for accepting your contribution, but conformance is advised.

These guidelines are intended to complement the Rust API Guidelines.

Top-down Modules

Readers of the module should be able to understand your code by reading it from top to bottom. Whenever items in your module form a parent-child relationship, the parent should be written above the children. Typically this means that important pub items are placed before private implementation details.

For instance, here are three functions. Notice how the definition of foo is placed above its dependencies. The parent is foo while its children are bar and baz.

pub fn foo() {
    bar();
    baz();
}

fn bar() {}

fn baz() {}

This guideline applies to types as well.

pub struct Foo {
    bars: Vec<Bar>,
}

struct Bar {
    // ...
}

Getters and Setters

Getters should not start with a get_ prefix.

Good	Bad
impl Foo { fn bar(&self) -> &Bar { ... } fn set_bar(&mut self, bar: Bar) { ... } }	impl Foo { fn get_bar(&self) -> &Bar { ... } fn set_bar(&mut self, bar: Bar) { ... } }

See SocketAddr for an example of a standard library type that uses this convention.

Under appropriate circumstances a different naming scheme can be used. Command is a standard type that demonstrates this.

If a bar field exists and no invariants need to be maintained by the getters and setters, it is usually better to make the bar field public.

Bevy Events

Types intended to be used as events in EventReader and EventWriter should end in the Event suffix. This is helpful for readers trying to distinguish events from other types in the program.

Good	Bad
struct CollisionEvent { ... } fn handle_collisions(mut events: EventReader<CollisionEvent>) { ... }	struct Collision { ... } fn handle_collisions(mut events: EventReader<Collision>) { ... }

Specifying Dependencies

When adding a new dependency to a crate, make sure you specify the full semver version.

Good	Bad
[dependencies] serde_json = "1.0.96"	[dependencies] serde_json = "1"

Writing Unit Tests

When writing unit tests, unwrap errors instead of returning them. Panicking displays the line and column of the error, which is useful for debugging. This information is lost when the error is returned.

Good	Bad
#[test] fn my_test() { some_fallible_func().unwrap(); }	#[test] fn my_test() -> anyhow::Result<()> { some_fallible_func()?; // ... Ok(()) }

Documentation

All public items should be documented. Documentation must be written with complete sentences and correct grammar. Consider using intra-doc links where appropriate.

Unit Tests

Unit tests help your contributions last! They ensure that your code works as expected and that it continues to work in the future.

whole-server unit tests can be found in crates/valence/src/tests/.

Naming Quantities

Variables intended to hold quantities should be written with the _count suffix instead of the num_ prefix.

Good	Bad
let block_count = ...;	let num_blocks = ...;