为类型别名元组添加 Impl (f64, f64)

Question

我有一个自定义类型 Point

type Point = (f64, f64);

我想将两个Points 加在一起，但出现此错误

error[E0368]: binary assignment operation `+=` cannot be applied to type `(f64, f64)`
   --> src/main.rs:119:21
    |
119 |                     force_map[&body.name] += force;
    |                     ---------------------^^^^^^^^^
    |                     |
    |                     cannot use `+=` on type `(f64, f64)`

当我尝试实现 Add 时，出现以下错误：

39 | / impl Add for (f64, f64) {
40 | |     #[inline(always)]
41 | |     fn add(self, other: (f64, f64)) -> (f64, f64)  {
42 | |         // Probably it will be optimized to not actually copy self and rhs for each call !
43 | |         (self.0 + other.0, self.1 + other.1);
44 | |     }
45 | | }
   | |_^ impl doesn't use types inside crate
   |
   = note: the impl does not reference any types defined in this crate
   = note: define and implement a trait or new type instead

Add是否可以实施type？我应该用 astruct代替吗？

Answer 1

不，你没有类型Point。不幸的是，该type关键字不会创建新类型，而只是为现有类型创建新名称（别名）。

要创建类型，请使用：

struct Point(f64, f64);