类型之间的 + 操作数是什么意思？

Question

这个例子来自 core::any

use std::fmt::Debug;
use std::any::Any;

// Logger function for any type that implements Debug.
fn log<T: Any + Debug>(value: &T) {
    let value_any = value as &dyn Any;

    // try to convert our value to a String.  If successful, we want to
    // output the String's length as well as its value.  If not, it's a
    // different type: just print it out unadorned.
    match value_any.downcast_ref::<String>() {
        Some(as_string) => {
            println!("String ({}): {}", as_string.len(), as_string);
        }
        None => {
            println!("{:?}", value);
        }
    }
}

// This function wants to log its parameter out prior to doing work with it.
fn do_work<T: Any + Debug>(value: &T) {
    log(value);
    // ...do some other work
}

fn main() {
    let my_string = "Hello World".to_string();
    do_work(&my_string);

    let my_i8: i8 = 100;
    do_work(&my_i8);
}

这是我第一次看到 + 类型之间的操作数 Any + Debug。我假设它像 algebraic types，因此将是 Any 类型和 Debug 类型；但是，我在 Rust 的代数类型下找不到任何文档。

+实际上在这里做什么，它叫什么？我在哪里可以找到这方面的文档？

Answer 1

T: <a href="https://doc.rust-lang.org/std/any/trait.Any.html" rel="nofollow noreferrer">Any</a> + <a href="https://doc.rust-lang.org/std/fmt/trait.Debug.html" rel="nofollow noreferrer">Debug</a> is a trait bound. The type T must satisfy Any and Debug, therefore the + sign is used here and it is not related to algebraic types. You can read more on traits at the corresponding section in the book.

This section 提到 + 符号。

类型之间的 + 操作数是什么意思？

What does the + operand between types mean?

static-typing

algebraic-data-types

rust