3b24f520b9
The LogPlugin now allows overriding the default
`tracing_subscriber::fmt::Layer` through a new `fmt_layer` option. This
enables customization of the default log output format without having to
replace the entire logging system.
For example, to disable timestamps in the log output:
```rust
fn fmt_layer(_app: &mut App) -> Option<bevy::log::BoxedFmtLayer> {
Some(Box::new(
bevy::log::tracing_subscriber::fmt::Layer::default()
.without_time()
.with_writer(std::io::stderr),
))
}
fn main() {
App::new()
.add_plugins(DefaultPlugins.set(bevy::log::LogPlugin {
fmt_layer,
..default()
}))
.run();
}
```
This is different from the existing `custom_layer` option, because that
option _adds_ additional layers to the subscriber, but can't modify the
default formatter layer (at least, not to my knowledge).
I almost always disable timestamps in my Bevy logs, and usually also
tweak other default log formatting (such as `with_span_events`), which
made it so that I always had to disable the default logger. This allows
me to use everything the Bevy logger supports (including tracy support),
while still formatting the default logs the way I like them.
---------
Signed-off-by: Jean Mertz <git@jeanmertz.com>
73 lines
2.2 KiB
Rust
73 lines
2.2 KiB
Rust
//! This example illustrates how to add custom log layers in bevy.
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use bevy::{
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log::{
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tracing::{self, Subscriber},
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tracing_subscriber::Layer,
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BoxedFmtLayer, BoxedLayer,
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},
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prelude::*,
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};
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struct CustomLayer;
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impl<S: Subscriber> Layer<S> for CustomLayer {
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fn on_event(
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&self,
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event: &tracing::Event<'_>,
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_ctx: bevy::log::tracing_subscriber::layer::Context<'_, S>,
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) {
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println!("Got event!");
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println!(" level={}", event.metadata().level());
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println!(" target={}", event.metadata().target());
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println!(" name={}", event.metadata().name());
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}
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}
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// We don't need App for this example, as we are just printing log information.
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// For an example that uses App, see log_layers_ecs.
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fn custom_layer(_app: &mut App) -> Option<BoxedLayer> {
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// You can provide multiple layers like this, since Vec<Layer> is also a layer:
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Some(Box::new(vec![
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bevy::log::tracing_subscriber::fmt::layer()
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.with_file(true)
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.boxed(),
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CustomLayer.boxed(),
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]))
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}
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// While `custom_layer` allows you to add _additional_ layers, it won't allow you to override the
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// default `tracing_subscriber::fmt::Layer` added by `LogPlugin`. To do that, you can use the
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// `fmt_layer` option.
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//
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// In this example, we're disabling the timestamp in the log output.
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fn fmt_layer(_app: &mut App) -> Option<BoxedFmtLayer> {
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Some(Box::new(
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bevy::log::tracing_subscriber::fmt::Layer::default()
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.without_time()
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.with_writer(std::io::stderr),
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))
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}
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fn main() {
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App::new()
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.add_plugins(DefaultPlugins.set(bevy::log::LogPlugin {
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custom_layer,
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fmt_layer,
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..default()
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}))
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.add_systems(Update, log_system)
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.run();
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}
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fn log_system() {
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// here is how you write new logs at each "log level" (in "most important" to
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// "least important" order)
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error!("something failed");
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warn!("something bad happened that isn't a failure, but thats worth calling out");
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info!("helpful information that is worth printing by default");
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debug!("helpful for debugging");
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trace!("very noisy");
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}
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