一种有趣的 golang"构造函数" 的写法

package main
    
    import (
        "fmt"
    )
    
    type options struct {
        a int64
        b string
        c map[int]string
    }
    
    func NewOption(opt ...ServerOption) *options {
        r := new(options)
        for _, o := range opt {
            o(r)
        }
        return r
    }
    
    type ServerOption func(*options)
    
    func WriteA(s int64) ServerOption {
        return func(o *options) {
            o.a = s
        }
    }
    
    func WriteB(s string) ServerOption {
        return func(o *options) {
            o.b = s
        }
    }
    
    func WriteC(s map[int]string) ServerOption {
        return func(o *options) {
            o.c = s
        }
    }
    
    func main() {
        opt1 := WriteA(int64(1))
        opt2 := WriteB("test")
        opt3 := WriteC(make(map[int]string,0))
    
        op := NewOption(opt1, opt2, opt3)
    
        fmt.Println(op.a, op.b, op.c)
    }

原文来自：GoCN