43 lines
1.1 KiB
Rust
43 lines
1.1 KiB
Rust
// This code (probably) _should_ compile, but it currently does not because we
|
|
// are not smart enough about implied bounds.
|
|
|
|
use std::io;
|
|
|
|
fn real_dispatch<T, F>(f: F) -> Result<(), io::Error>
|
|
where
|
|
F: FnOnce(&mut UIView<T>) -> Result<(), io::Error> + Send + 'static,
|
|
{
|
|
todo!()
|
|
}
|
|
|
|
#[derive(Debug)]
|
|
struct UIView<'a, T: 'a> {
|
|
_phantom: std::marker::PhantomData<&'a mut T>,
|
|
}
|
|
|
|
trait Handle<'a, T: 'a, V, R> {
|
|
fn dispatch<F>(&self, f: F) -> Result<(), io::Error>
|
|
where
|
|
F: FnOnce(&mut V) -> R + Send + 'static;
|
|
}
|
|
|
|
#[derive(Debug, Clone)]
|
|
struct TUIHandle<T> {
|
|
_phantom: std::marker::PhantomData<T>,
|
|
}
|
|
|
|
impl<'a, T: 'a> Handle<'a, T, UIView<'a, T>, Result<(), io::Error>> for TUIHandle<T> {
|
|
fn dispatch<F>(&self, f: F) -> Result<(), io::Error>
|
|
where
|
|
F: FnOnce(&mut UIView<'a, T>) -> Result<(), io::Error> + Send + 'static,
|
|
{
|
|
real_dispatch(f)
|
|
//~^ ERROR lifetime may not live long enough
|
|
//~| ERROR implementation of `FnOnce` is not general enough
|
|
//~| ERROR mismatched types
|
|
//
|
|
}
|
|
}
|
|
|
|
fn main() {}
|