function - 如何避免将大量参数传递给嵌套函数？

Question

我读到没有办法将所有外部局部参数传递给嵌套函数，但也许有一些 hack 可以做到这一点？如何避免将大量参数传递给此函数，例如:

let var1 = 5;
let var2 = 12.2;
let var3 = bar();
let var4 = tar() * var1;
// etc ... a lot of variables ...
fn foo() {
    // want to have var1, var2, var3, var4 ...
}

Answer 1

你想要的是一个closure :

fn main() {
    let var1 = 5;
    let var2 = 12.2;
    let foo = || {
        var1 as f64 + var2
    };
    println!("foo(): {}", foo()); // prints "foo(): 17.2"
}