6f99a27886
This implements RFC 39. Omitted lifetimes in return values will now be
inferred to more useful defaults, and an error is reported if a lifetime
in a return type is omitted and one of the two lifetime elision rules
does not specify what it should be.
This primarily breaks two uncommon code patterns. The first is this:
unsafe fn get_foo_out_of_thin_air() -> &Foo {
...
}
This should be changed to:
unsafe fn get_foo_out_of_thin_air() -> &'static Foo {
...
}
The second pattern that needs to be changed is this:
enum MaybeBorrowed<'a> {
Borrowed(&'a str),
Owned(String),
}
fn foo() -> MaybeBorrowed {
Owned(format!("hello world"))
}
Change code like this to:
enum MaybeBorrowed<'a> {
Borrowed(&'a str),
Owned(String),
}
fn foo() -> MaybeBorrowed<'static> {
Owned(format!("hello world"))
}
Closes #15552.
[breaking-change]
127 lines
3.2 KiB
Rust
127 lines
3.2 KiB
Rust
// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use std::cmp;
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#[deriving(Show)]
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enum cat_type { tuxedo, tabby, tortoiseshell }
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impl cmp::PartialEq for cat_type {
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fn eq(&self, other: &cat_type) -> bool {
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((*self) as uint) == ((*other) as uint)
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}
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fn ne(&self, other: &cat_type) -> bool { !(*self).eq(other) }
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}
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// Very silly -- this just returns the value of the name field
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// for any int value that's less than the meows field
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// ok: T should be in scope when resolving the trait ref for map
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struct cat<T> {
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// Yes, you can have negative meows
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meows : int,
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how_hungry : int,
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name : T,
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}
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impl<T> cat<T> {
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pub fn speak(&mut self) { self.meow(); }
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pub fn eat(&mut self) -> bool {
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if self.how_hungry > 0 {
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println!("OM NOM NOM");
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self.how_hungry -= 2;
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return true;
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} else {
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println!("Not hungry!");
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return false;
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}
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}
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}
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impl<T> Collection for cat<T> {
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fn len(&self) -> uint { self.meows as uint }
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fn is_empty(&self) -> bool { self.meows == 0 }
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}
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impl<T> Mutable for cat<T> {
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fn clear(&mut self) {}
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}
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impl<T> Map<int, T> for cat<T> {
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fn contains_key(&self, k: &int) -> bool { *k <= self.meows }
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fn find(&self, k: &int) -> Option<&T> {
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if *k <= self.meows {
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Some(&self.name)
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} else {
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None
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}
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}
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}
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impl<T> MutableMap<int, T> for cat<T> {
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fn insert(&mut self, k: int, _: T) -> bool {
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self.meows += k;
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true
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}
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fn find_mut(&mut self, _k: &int) -> Option<&mut T> { fail!() }
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fn remove(&mut self, k: &int) -> bool {
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if self.find(k).is_some() {
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self.meows -= *k; true
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} else {
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false
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}
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}
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fn pop(&mut self, _k: &int) -> Option<T> { fail!() }
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fn swap(&mut self, _k: int, _v: T) -> Option<T> { fail!() }
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}
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impl<T> cat<T> {
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pub fn get(&self, k: &int) -> &T {
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match self.find(k) {
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Some(v) => { v }
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None => { fail!("epic fail"); }
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}
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}
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pub fn new(in_x: int, in_y: int, in_name: T) -> cat<T> {
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cat{meows: in_x, how_hungry: in_y, name: in_name }
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}
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}
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impl<T> cat<T> {
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fn meow(&mut self) {
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self.meows += 1;
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println!("Meow {}", self.meows);
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if self.meows % 5 == 0 {
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self.how_hungry += 1;
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}
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}
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}
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pub fn main() {
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let mut nyan: cat<String> = cat::new(0, 2, "nyan".to_string());
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for _ in range(1u, 5) { nyan.speak(); }
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assert!(*nyan.find(&1).unwrap() == "nyan".to_string());
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assert_eq!(nyan.find(&10), None);
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let mut spotty: cat<cat_type> = cat::new(2, 57, tuxedo);
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for _ in range(0u, 6) { spotty.speak(); }
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assert_eq!(spotty.len(), 8);
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assert!((spotty.contains_key(&2)));
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assert_eq!(spotty.get(&3), &tuxedo);
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}
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