// Copyright 2014 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. #![feature(unboxed_closures, core)] use std::ops::Fn; struct Foo(T); impl Fn<()> for Foo { extern "rust-call" fn call(&self, _: ()) -> T { match *self { Foo(t) => t } } } impl FnMut<()> for Foo { extern "rust-call" fn call_mut(&mut self, _: ()) -> T { self.call(()) } } impl FnOnce<()> for Foo { type Output = T; extern "rust-call" fn call_once(self, _: ()) -> T { self.call(()) } } fn main() { let t: u8 = 1; println!("{}", Foo(t)()); }