英文:
Differences of embedded and field
问题
以下是翻译的内容：
这里有一个嵌入了结构体Struct1和一个作为字段定义的结构体Struct2。虽然fmt.Printf()的输出结果相同，但初始化方式有所不同。我对此感到困惑。非常抱歉。
Struct1和Struct2之间有什么区别？- 在什么情况下应该使用它们？
代码
type sample1 struct {
Data string
}
type sample2 struct {
Data string
}
type Struct1 struct {
*sample1
*sample2
}
type Struct2 struct {
Sample1 sample1
Sample2 sample2
}
func main() {
s1 := &Struct1{
&sample1{},
&sample2{},
}
s1.sample1.Data = "s1 sample1 data"
s1.sample2.Data = "s1 sample2 data"
s2 := &Struct2{}
s2.Sample1.Data = "s2 sample1 data"
s2.Sample2.Data = "s2 sample2 data"
fmt.Printf("%s, %s\n", s1.sample1.Data, s1.sample2.Data)
fmt.Printf("%s, %s\n", s2.Sample1.Data, s2.Sample2.Data)
}
https://play.golang.org/p/gUy6gwVJDP
非常感谢您的时间和建议。对于我的问题不成熟，我感到非常抱歉。
英文:
There are embedded struct Struct1 and a struct Struct2 defined as field. Both fmt.Printf() are same results while there is a difference for the initialization. I confused about this. I'm sorry.
- What differences are these between
Struct1andStruct2? - Which should be used under what situation?
Script
type sample1 struct {
Data string
}
type sample2 struct {
Data string
}
type Struct1 struct {
*sample1
*sample2
}
type Struct2 struct {
Sample1 sample1
Sample2 sample2
}
func main() {
s1 := &Struct1{
&sample1{},
&sample2{},
}
s1.sample1.Data = "s1 sample1 data"
s1.sample2.Data = "s1 sample2 data"
s2 := &Struct2{}
s2.Sample1.Data = "s2 sample1 data"
s2.Sample2.Data = "s2 sample2 data"
fmt.Printf("%s, %s\n", s1.sample1.Data, s1.sample2.Data)
fmt.Printf("%s, %s\n", s2.Sample1.Data, s2.Sample2.Data)
}
https://play.golang.org/p/gUy6gwVJDP
Thank you so much for your time and advices. And I'm sorry for my immature question.
答案1
得分: 1
关于第二个问题，个人而言，我主要使用嵌入来提升方法。
//定义接口
type Doer interface{
Do()
}
//实现接口
func DoWith(d Doer){}
type sample1 struct{}
func (s sample1)Do(){}
type Struct1 struct {
sample1
}
type Struct2 struct {
Sample1 sample1
}
var s1 Struct1
var s2 Struct2
//可以调用
DoWith(s1) //方法被提升，所以满足接口要求
//但是无法调用
DoWith(s2)
关于解码JSON，
type Sample1 struct {
Data string `json:"data"`
}
type Sample2 struct {
Number int `json:"number"`
}
type Struct1 struct {
Sample1
Sample2
}
var s1 Struct1
json.Unmarshal([]byte(`{"data": "foo", "number": 5}`), &s1)
fmt.Println(s1.Data, s1.Number) //输出 foo 5
英文:
As about second question, personally I mostly use embedding to promote methods
//having
type Doer interface{
Do()
}
func DoWith(d Doer){}
func (s sample1)Do(){} //implemented
type Struct1 struct {
sample1
}
type Struct2 struct {
Sample1 sample1
}
var s1 Struct1
var s2 Struct2
//you can call
DoWith(s1) //method promoted so interface satisfied
//but cannot
DoWith(s2)
and to decode JSON,
//having
type Sample1 struct {
Data string `json:"data"`
}
type Sample2 struct {
Number int `json:"number"`
}
//you can easy and handy compose
type Struct1 struct {
Sample1
Sample2
}
var s1 Struct1
json.Unmarshal([]byte(`{"data": "foo", "number": 5}`), &s1)
fmt.Println(s1.Data, s1.Number) //print foo 5
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