如何估算方法重载? [英] How can I approximate method overloading?

问题描述

我正在建模一个API，其中方法重载将是一个很好的选择.我的幼稚尝试失败了:

I am modeling an API where method overloading would be a good fit. My naïve attempt failed:

// fn attempt_1(_x: i32) {}
// fn attempt_1(_x: f32) {}
// Error: duplicate definition of value `attempt_1`

然后我添加了一个枚举并进行以下操作:

I then added an enum and worked through to:

enum IntOrFloat {
    Int(i32),
    Float(f32),
}

fn attempt_2(_x: IntOrFloat) {}

fn main() {
    let i: i32 = 1;
    let f: f32 = 3.0;

    // Can't pass the value directly
    // attempt_2(i);
    // attempt_2(f);
    // Error: mismatched types: expected enum `IntOrFloat`

    attempt_2(IntOrFloat::Int(i));
    attempt_2(IntOrFloat::Float(f));
    // Ugly that the caller has to explicitly wrap the parameter
}

进行一些快速搜索，我找到了 一些

Doing some quick searches, I've found some references that talk about overloading, and all of them seem to end in "we aren't going to allow this, but give traits a try". So I tried:

enum IntOrFloat {
    Int(i32),
    Float(f32),
}

trait IntOrFloatTrait {
    fn to_int_or_float(&self) -> IntOrFloat;
}

impl IntOrFloatTrait for i32 {
    fn to_int_or_float(&self) -> IntOrFloat {
        IntOrFloat::Int(*self)
    }
}

impl IntOrFloatTrait for f32 {
    fn to_int_or_float(&self) -> IntOrFloat {
        IntOrFloat::Float(*self)
    }
}

fn attempt_3(_x: &dyn IntOrFloatTrait) {}

fn main() {
    let i: i32 = 1;
    let f: f32 = 3.0;

    attempt_3(&i);
    attempt_3(&f);
    // Better, but the caller still has to explicitly take the reference
}

这是最接近方法重载的地方吗?有没有更清洁的方法?

Is this the closest I can get to method overloading? Is there a cleaner way?

推荐答案

是的，确实存在，您几乎已经掌握了它.性状是解决之道，但是您不需要特质对象，请使用泛型:

Yes, there is, and you almost got it already. Traits are the way to go, but you don't need trait objects, use generics:

#[derive(Debug)]
enum IntOrFloat {
    Int(i32),
    Float(f32),
}

trait IntOrFloatTrait {
    fn to_int_or_float(&self) -> IntOrFloat;
}

impl IntOrFloatTrait for i32 {
    fn to_int_or_float(&self) -> IntOrFloat {
        IntOrFloat::Int(*self)
    }
}

impl IntOrFloatTrait for f32 {
    fn to_int_or_float(&self) -> IntOrFloat {
        IntOrFloat::Float(*self)
    }
}

fn attempt_4<T: IntOrFloatTrait>(x: T) {
    let v = x.to_int_or_float();
    println!("{:?}", v);
}

fn main() {
    let i: i32 = 1;
    let f: f32 = 3.0;

    attempt_4(i);
    attempt_4(f);
}

在此处看到它正常工作.

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