9e3d0b002a
This breaks a fair amount of code. The typical patterns are:
* `for _ in range(0, 10)`: change to `for _ in range(0u, 10)`;
* `println!("{}", 3)`: change to `println!("{}", 3i)`;
* `[1, 2, 3].len()`: change to `[1i, 2, 3].len()`.
RFC #30. Closes #6023.
[breaking-change]
51 lines
1.6 KiB
Rust
51 lines
1.6 KiB
Rust
// Copyright 2013 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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struct Vec2 {
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x: f64,
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y: f64
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}
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// methods we want to export as methods as well as operators
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impl Vec2 {
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#[inline(always)]
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fn vmul(self, other: f64) -> Vec2 {
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Vec2 { x: self.x * other, y: self.y * other }
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}
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}
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// Right-hand-side operator visitor pattern
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trait RhsOfVec2Mul<Result> { fn mul_vec2_by(&self, lhs: &Vec2) -> Result; }
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// Vec2's implementation of Mul "from the other side" using the above trait
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impl<Res, Rhs: RhsOfVec2Mul<Res>> Mul<Rhs,Res> for Vec2 {
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fn mul(&self, rhs: &Rhs) -> Res { rhs.mul_vec2_by(self) }
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}
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// Implementation of 'f64 as right-hand-side of Vec2::Mul'
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impl RhsOfVec2Mul<Vec2> for f64 {
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fn mul_vec2_by(&self, lhs: &Vec2) -> Vec2 { lhs.vmul(*self) }
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}
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// Usage with failing inference
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pub fn main() {
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let a = Vec2 { x: 3.0f64, y: 4.0f64 };
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// the following compiles and works properly
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let v1: Vec2 = a * 3.0f64;
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println!("{} {}", v1.x, v1.y);
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// the following compiles but v2 will not be Vec2 yet and
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// using it later will cause an error that the type of v2
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// must be known
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let v2 = a * 3.0f64;
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println!("{} {}", v2.x, v2.y); // error regarding v2's type
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}
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