b77e3ef33a
# Objective Stumbled upon a `from <-> form` transposition while reviewing a PR, thought it was interesting, and went down a bit of a rabbit hole. ## Solution Fix em
78 lines
2.6 KiB
Rust
78 lines
2.6 KiB
Rust
//! Illustrates how to make a single system from multiple functions running in sequence,
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//! passing the output of the first into the input of the next.
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use bevy::prelude::*;
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use std::num::ParseIntError;
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use bevy::log::{debug, error, info, Level, LogPlugin};
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fn main() {
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App::new()
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.insert_resource(Message("42".to_string()))
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.insert_resource(OptionalWarning(Err("Got to rusty?".to_string())))
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.add_plugins(LogPlugin {
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level: Level::TRACE,
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filter: "".to_string(),
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..default()
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})
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.add_systems(
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Update,
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(
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parse_message_system.pipe(handler_system),
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data_pipe_system.map(|out| info!("{out}")),
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parse_message_system.map(|out| debug!("{out:?}")),
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warning_pipe_system.map(|out| {
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if let Err(err) = out {
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error!("{err}");
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}
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}),
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parse_error_message_system.map(|out| {
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if let Err(err) = out {
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error!("{err}");
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}
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}),
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parse_message_system.map(drop),
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),
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)
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.run();
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}
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#[derive(Resource, Deref)]
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struct Message(String);
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#[derive(Resource, Deref)]
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struct OptionalWarning(Result<(), String>);
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// This system produces a Result<usize> output by trying to parse the Message resource.
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fn parse_message_system(message: Res<Message>) -> Result<usize, ParseIntError> {
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message.parse::<usize>()
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}
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// This system produces a Result<()> output by trying to parse the Message resource.
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fn parse_error_message_system(message: Res<Message>) -> Result<(), ParseIntError> {
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message.parse::<usize>()?;
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Ok(())
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}
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// This system takes a Result<usize> input and either prints the parsed value or the error message
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// Try changing the Message resource to something that isn't an integer. You should see the error
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// message printed.
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fn handler_system(In(result): In<Result<usize, ParseIntError>>) {
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match result {
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Ok(value) => println!("parsed message: {value}"),
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Err(err) => println!("encountered an error: {err:?}"),
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}
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}
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// This system produces a String output by trying to clone the String from the Message resource.
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fn data_pipe_system(message: Res<Message>) -> String {
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message.0.clone()
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}
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// This system produces a Result<String> output by trying to extract a String from the
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// OptionalWarning resource. Try changing the OptionalWarning resource to None. You should
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// not see the warning message printed.
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fn warning_pipe_system(message: Res<OptionalWarning>) -> Result<(), String> {
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message.0.clone()
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}
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