Rust 编码规范 V 1.0 beta

G.TYP.FLT.04 宜使用Rust内置方法处理浮点数计算

【级别】 建议

【描述】

内置方法可能会牺牲一定性能，但可以提升准确性。

【反例】

#![warn(clippy::imprecise_flops, clippy::suboptimal_flops)]

// 不符合
fn main() {
    let a = 3f32;
    let _ = a.powf(1.0 / 3.0);
    let _ = (1.0 + a).ln();
    let _ = a.exp() - 1.0;

    use std::f32::consts::E;

    let a = 3f32;
    let _ = (2f32).powf(a);
    let _ = E.powf(a);
    let _ = a.powf(1.0 / 2.0);
    let _ = a.log(2.0);
    let _ = a.log(10.0);
    let _ = a.log(E);
    let _ = a.powf(2.0);
    let _ = a * 2.0 + 4.0;
    let _ = if a < 0.0 {
        -a
    } else {
        a
    };
    let _ = if a < 0.0 {
        a
    } else {
        -a
    };
}

【正例】

#![warn(clippy::imprecise_flops, clippy::suboptimal_flops)]

// 符合
fn main(){
    let a = 3f32;
    let _ = a.cbrt();
    let _ = a.ln_1p();
    let _ = a.exp_m1();

    use std::f32::consts::E;

    let a = 3f32;
    let _ = a.exp2();
    let _ = a.exp();
    let _ = a.sqrt();
    let _ = a.log2();
    let _ = a.log10();
    let _ = a.ln();
    let _ = a.powi(2);
    let _ = a.mul_add(2.0, 4.0);
    let _ = a.abs();
    let _ = -a.abs();
}

【Lint 检测】