bevy/examples/ecs/system_chaining.rs
Alice Cecile 6f5a4d9deb
Rename add_resource to insert_resource (#1356)
* Renamed add_resource to insert_resource

* Changed usage of add_resource to insert_resource

* Renamed add_thread_local_resource
2021-01-30 12:55:13 -08:00

25 lines
859 B
Rust

use anyhow::Result;
use bevy::prelude::*;
fn main() {
App::build()
.insert_resource(Message("42".to_string()))
.add_system(parse_message_system.system().chain(handler_system.system()))
.run();
}
struct Message(String);
// this system produces a Result<usize> output by trying to parse the Message resource
fn parse_message_system(message: Res<Message>) -> Result<usize> {
Ok(message.0.parse::<usize>()?)
}
// This system takes a Result<usize> input and either prints the parsed value or the error message
// Try changing the Message resource to something that isn't an integer. You should see the error message printed.
fn handler_system(In(result): In<Result<usize>>) {
match result {
Ok(value) => println!("parsed message: {}", value),
Err(err) => println!("encountered an error: {:?}", err),
}
}