rust - 元组是否实现 `Copy` ？

Question

在 Rust Book 第 18 章中，他们给出了模式匹配中元组的示例。

fn print_coordinates(&(x, y): &(i32, i32)) {
    println!("Current location: ({}, {})", x, y);
}

fn main() {
    let point = (3, 5);
    print_coordinates(&point);   // point passed as reference
}

出于好奇，我试过不通过这样的引用。

fn print_coordinates((x, y): (i32, i32)) {
    println!("Current location: ({}, {})", x, y);
}

fn main() {
    let point = (3, 5);
    print_coordinates(point);   // point passed as value
    print_coordinates(point);   // point is still valid here
}

它编译并打印出坐标 2 次。

能否像其他原始数据类型(数字、 bool 值等)一样将元组传递给函数？

Answer 1

是的；根据 the docs ，这对于元数为 12 或更小的元组是正确的:

If every type inside a tuple implements one of the following traits, then a tuple itself also implements it.

• Clone
• Copy
• PartialEq
• Eq
• PartialOrd
• Ord
• Debug
• Default
• Hash

Due to a temporary restriction in Rust's type system, these traits are only implemented on tuples of arity 12 or less. In the future, this may change.