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use super::Disposable; /// Defer an action until the end of a lexical scope. /// /// This function returns a value that calls the provided closure when dropped, resulting in /// functionality akin to `try...finally` blocks or Swift's `defer` blocks and Go's `defer func`. /// /// # Examples /// /// ``` /// use dispose::defer; /// /// { /// let _d = defer(|| println!("Hello from defer()!")); /// /// println!("Hello, world!"); /// } /// // This prints the following: /// // Hello, world! /// // Hello from defer()! /// ``` /// /// A more pertinent example would be the use of defer with the `?` operator: /// /// ``` /// use dispose::defer; /// /// fn tryme() -> Result<(), ()> { /// let _d = defer(|| println!("Cleaning up...")); /// /// println!("Hello!"); /// /// let uh_oh = Err(())?; // Pretend this was a function that failed /// /// println!("You can't see me: {:?}", uh_oh); /// /// Ok(()) /// } /// /// println!("hi"); /// /// tryme().map_err(|()| println!("ERROR: Something went wrong.")).unwrap_err() /// /// // This prints the following: /// // Hello! /// // Cleaning up... /// // ERROR: Something went wrong. /// ``` pub fn defer<F: FnOnce()>(f: F) -> Disposable<F> { f.into() } /// Defer an action until the end of a lexical scope, passing the provided argument; similar to /// [`defer`]. /// /// This function is mainly provided for completeness, and is less useful than using [`FnOnce(W)` /// as `DisposeWith<W>`][`FnOnce(W)`] for providing a struct with dynamic teardown logic with a /// provided value. /// /// [`defer`]: ./fn.defer.html /// [`FnOnce(W)`]: ./trait.DisposeWith.html#impl-DisposeWith<W> pub fn defer_with<W, F: FnOnce(W)>(with: W, f: F) -> Disposable<(W, F)> { (with, f.into()).into() }