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|
use ecs::event::component::Changed;
use ecs::pair::Pair;
use ecs::phase::UPDATE as UPDATE_PHASE;
use ecs::system::observer::Observe;
use ecs::{Component, Query, World};
#[derive(Component)]
struct SomeData
{
num: u64,
}
#[derive(Component)]
struct Greeting
{
greeting: String,
}
fn say_hello(query: Query<(&SomeData, &mut Greeting)>)
{
for (data, mut greeting) in &query {
println!("{}: {}", greeting.greeting, data.num);
if greeting.greeting == "Good evening" {
greeting.greeting = "Good morning".to_string();
greeting.set_changed();
}
}
}
fn print_changed_greetings(observe: Observe<'_, Pair<Changed, Greeting>>)
{
println!("\nChanged greetings:");
for ent in &observe {
let Some(greeting) = ent.get::<Greeting>() else {
unreachable!();
};
println!("A greeting changed to {}", greeting.greeting);
}
println!("");
}
fn main()
{
let mut world = World::new();
world.register_system(*UPDATE_PHASE, say_hello);
world.register_observer(print_changed_greetings);
world.create_entity((
SomeData { num: 987_654 },
Greeting {
greeting: "Good afternoon".to_string(),
},
));
world.create_entity((
SomeData { num: 345 },
Greeting { greeting: "Good evening".to_string() },
));
world.step();
world.step();
for (mut greeting,) in &world.query::<(&mut Greeting,), ()>() {
if greeting.greeting == "Good afternoon" {
greeting.greeting = "Yo yo".to_string();
greeting.set_changed();
}
}
world.step();
world.step();
}
|
