| //@ build-pass |
| //@ edition:2018 |
| |
| type BoxFuture<T> = std::pin::Pin<Box<dyn std::future::Future<Output=T>>>; |
| |
| fn main() { |
| f(); |
| } |
| |
| async fn f() { |
| run("dependency").await; |
| } |
| |
| struct InMemoryStorage; |
| |
| struct User<'dep> { |
| dep: &'dep str, |
| } |
| |
| impl<'a> StorageRequest<InMemoryStorage> for SaveUser<'a> { |
| fn execute(&self) -> BoxFuture<Result<(), String>> { |
| todo!() |
| } |
| } |
| |
| trait Storage { |
| type Error; |
| } |
| |
| impl Storage for InMemoryStorage { |
| type Error = String; |
| } |
| |
| trait StorageRequestReturnType { |
| type Output; |
| } |
| |
| trait StorageRequest<S: Storage>: StorageRequestReturnType { |
| fn execute( |
| &self, |
| ) -> BoxFuture<Result<<Self as StorageRequestReturnType>::Output, <S as Storage>::Error>>; |
| } |
| |
| struct SaveUser<'a> { |
| name: &'a str, |
| } |
| |
| impl<'a> StorageRequestReturnType for SaveUser<'a> { |
| type Output = (); |
| } |
| |
| impl<'dep> User<'dep> { |
| async fn save<S>(self) |
| where |
| S: Storage, |
| for<'a> SaveUser<'a>: StorageRequest<S>, |
| { |
| SaveUser { name: "Joe" } |
| .execute() |
| .await; |
| } |
| } |
| |
| async fn run<S>(dep: &str) |
| where |
| S: Storage, |
| for<'a> SaveUser<'a>: StorageRequest<S>, |
| for<'a> SaveUser<'a>: StorageRequestReturnType, |
| { |
| User { dep }.save().await; |
| } |