40 lines
997 B
Rust
40 lines
997 B
Rust
// This code (probably) _should_ compile, but it currently does not because we
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// are not smart enough about implied bounds.
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use std::io;
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fn real_dispatch<T, F>(f: F) -> Result<(), io::Error>
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where
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F: FnOnce(&mut UIView<T>) -> Result<(), io::Error> + Send + 'static,
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{
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todo!()
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}
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#[derive(Debug)]
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struct UIView<'a, T: 'a> {
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_phantom: std::marker::PhantomData<&'a mut T>,
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}
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trait Handle<'a, T: 'a, V, R> {
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fn dispatch<F>(&self, f: F) -> Result<(), io::Error>
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where
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F: FnOnce(&mut V) -> R + Send + 'static;
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}
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#[derive(Debug, Clone)]
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struct TUIHandle<T> {
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_phantom: std::marker::PhantomData<T>,
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}
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impl<'a, T: 'a> Handle<'a, T, UIView<'a, T>, Result<(), io::Error>> for TUIHandle<T> {
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fn dispatch<F>(&self, f: F) -> Result<(), io::Error>
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where
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F: FnOnce(&mut UIView<'a, T>) -> Result<(), io::Error> + Send + 'static,
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{
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real_dispatch(f)
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//~^ ERROR expected a `FnOnce(&mut UIView<'_, T>)` closure, found `F`
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}
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}
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fn main() {}
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