golang泛型

May 16, 2023

泛型与类型约束

package main

import "fmt"

var ints = map[string]int64{"0": 8, "1": 0, "2": 8, "3": 6}
var floats = map[string]float64{"k1": 1.1, "k2": 2.2}

// comparable 是预定义的类型约束
func SumIntsOrFloats[K comparable, V int64 | float64](m map[K]V) V {
    var s V
    for _, v := range m {
        s += v
    }
    return s
}

func init() {
    // 手动指定泛型参数
    fmt.Printf("Generic Sums: %v and %v\n",
        SumIntsOrFloats[string, int64](ints),
        SumIntsOrFloats[string, float64](floats))

    // 编译器自动推导泛型参数
    fmt.Printf("Generic Sums, type parameters inferred: %v and %v\n",
        SumIntsOrFloats(ints),
        SumIntsOrFloats(floats))
}

// 下面的语法可以定义一个类型约束
type Number interface {
    int64 | float64
}

// 使用自定义类型约束
func SumNumbers[K comparable, V Number](m map[K]V) V {
    var s V
    for _, v := range m {
        s += v
    }
    return s
}

func init() {
    fmt.Printf("Generic Sums with Constraint: %v and %v\n",
        SumNumbers(ints),
        SumNumbers(floats))
}

func main() {}