optionPattern.go

package main

import (
	"fmt"
)

type options struct {
	a int64
	b string
	c map[int]string
}
type ServerOption func(*options)


func NewOption(opt ...ServerOption) *options {
	r := new(options)
	for _, o := range opt {
		o(r)
	}
	return r
}


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")
	s := make(map[int]string)
	s[0] = "abc"
	s[1] = "cde"
	opt3 := WriteC(s)

	op := NewOption(opt1, opt2, opt3)

	fmt.Println(op.a, op.b, op.c)
}

这段代码主要解决golang中函数参数不可默认,导致不方便使用多种参数组合实例化对象