go options 模式

...

函数式选项模式的使用场景有哪些呢：我们一般用来配置一些基础的服务配置，比如MySQL，Redis，Kafka的配置，很多可选参数，可以方便动态灵活的配置想要配置的参数。

https://zhuanlan.zhihu.com/p/436468481

type Option func(*User)

func WithAge(age int) Option {
    return func(u *User) {
        u.Age = age
    }
}

func WithEmail(email string) Option {
    return func(u *User) {
        u.Email = email
    }
}

func WithPhone(phone string) Option {
    return func(u *User) {
        u.Phone = phone
    }
}

func WithGender(gender string) Option {
    return func(u *User) {
        u.Gender = gender
    }
}

func NewUser(id string, name string, options ...func(*User)) (*User, error) {
    user := User{
        ID:     id,
        Name:   name,
        Age:    0,
        Email:  "",
        Phone:  "",
        Gender: "female",
    }
    for _, option := range options {
        option(&user)
    }
    //...
    return &user, nil
}

user1, err := NewUser("1", "ada")
user2, err := NewUser("2", "bob", WithPhone("123456"), WithGender("male"))

 ...2

package main

import "fmt"

type Customer struct {
    id          int
    name    string
    gender  string
    phone   string
    age int8
}

type Option func(customer *Customer)

func WithId(id int) Option {
    return func(customer *Customer) {
        customer.id = id
    }
}

func WithGender(gender string) Option {
    return func(customer *Customer) {
        customer.gender = gender
    }
}

func WithName(name string) Option {
    return func(customer *Customer) {
        customer.name = name
    }
}

func WithPhone(phone string) Option {
    return func(customer *Customer) {
        customer.phone = phone
    }
}

func WithAge(age int8) Option {
    return func(customer *Customer) {
        customer.age = age
    }
}

func NewCustomer(options ...Option) Customer {
    customer := Customer{}
    for _, option := range options {
        // 用户自定义的初始化函数
        option(&customer)
    }
    return customer
}


func main() {
    customer := NewCustomer(WithAge(20),WithId(1), WithName("lazyr"), WithGender("man"), WithPhone("192993939393"))
    fmt.Println(customer)
}