bevy/examples/app/log_layers.rs
Zachary Harrold a371ee3019
Remove tracing re-export from bevy_utils (#17161)
# Objective

- Contributes to #11478

## Solution

- Made `bevy_utils::tracing` `doc(hidden)`
- Re-exported `tracing` from `bevy_log` for end-users
- Added `tracing` directly to crates that need it.

## Testing

- CI

---

## Migration Guide

If you were importing `tracing` via `bevy::utils::tracing`, instead use
`bevy::log::tracing`. Note that many items within `tracing` are also
directly re-exported from `bevy::log` as well, so you may only need
`bevy::log` for the most common items (e.g., `warn!`, `trace!`, etc.).
This also applies to the `log_once!` family of macros.

## Notes

- While this doesn't reduce the line-count in `bevy_utils`, it further
decouples the internal crates from `bevy_utils`, making its eventual
removal more feasible in the future.
- I have just imported `tracing` as we do for all dependencies. However,
a workspace dependency may be more appropriate for version management.
2025-01-05 23:06:34 +00:00

59 lines
1.6 KiB
Rust

//! This example illustrates how to add custom log layers in bevy.
use bevy::{
log::{
tracing::{self, Subscriber},
tracing_subscriber::Layer,
BoxedLayer,
},
prelude::*,
};
struct CustomLayer;
impl<S: Subscriber> Layer<S> for CustomLayer {
fn on_event(
&self,
event: &tracing::Event<'_>,
_ctx: bevy::log::tracing_subscriber::layer::Context<'_, S>,
) {
println!("Got event!");
println!(" level={}", event.metadata().level());
println!(" target={}", event.metadata().target());
println!(" name={}", event.metadata().name());
}
}
// We don't need App for this example, as we are just printing log information.
// For an example that uses App, see log_layers_ecs.
fn custom_layer(_app: &mut App) -> Option<BoxedLayer> {
// You can provide multiple layers like this, since Vec<Layer> is also a layer:
Some(Box::new(vec![
bevy::log::tracing_subscriber::fmt::layer()
.with_file(true)
.boxed(),
CustomLayer.boxed(),
]))
}
fn main() {
App::new()
.add_plugins(DefaultPlugins.set(bevy::log::LogPlugin {
custom_layer,
..default()
}))
.add_systems(Update, log_system)
.run();
}
fn log_system() {
// here is how you write new logs at each "log level" (in "most important" to
// "least important" order)
error!("something failed");
warn!("something bad happened that isn't a failure, but thats worth calling out");
info!("helpful information that is worth printing by default");
debug!("helpful for debugging");
trace!("very noisy");
}