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call

bevy::app::hotpatch

Function call 

Source 
pub fn call<O>(f: impl FnMut() -> O) -> O
Available on crate feature hotpatching only.
Expand description

Call a given function with hot-reloading enabled. If the function’s code changes, call will use the new version of the function. If code above the function changes, this will emit a panic that forces an unwind to the next call instance.

WASM/rust does not support unwinding, so call will not track dependency graph changes. If you are building a framework for use on WASM, you will need to use Subsecond::HotFn directly.

However, if you wrap your calling code in a future, you can simply drop the future which will cause drop to execute and get something similar to unwinding. Not great if refcells are open.

Examples found in repository?
examples/ecs/hotpatching_systems.rs (line 88)
81fn start_thread(receiver: crossbeam_channel::Receiver<()>) {
82    std::thread::spawn(move || {
83        while receiver.recv().is_ok() {
84            let start = bevy::platform::time::Instant::now();
85
86            // You can also make any part outside of a system hot patchable by wrapping it
87            // In this part, only the duration is hot patchable:
88            let duration = bevy::app::hotpatch::call(|| Duration::from_secs(2));
89
90            std::thread::sleep(duration);
91            info!("done after {:?}", start.elapsed());
92        }
93    });
94}