94 lines
1.5 KiB
Markdown
94 lines
1.5 KiB
Markdown
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# 03-embedding - 组合与类型断言
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## 知识点讲解
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### 结构体嵌入（组合）
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```go
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type Address struct {
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City string
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Street string
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}
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type Person struct {
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Name string
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Address Address // 嵌套结构体
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}
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type Employee struct {
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Person // 匿名嵌入
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EmployeeID int
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}
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emp := Employee{
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Person: Person{Name: "张三"},
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}
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fmt.Println(emp.Name) // 可以直接访问嵌入的字段
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```
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### 接口嵌入
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```go
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type Reader interface {
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Read() string
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}
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type Writer interface {
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Write(s string)
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}
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type ReadWriter interface {
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Reader
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Writer // 接口组合
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}
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```
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### 类型断言
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```go
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var i interface{} = "hello"
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// 方式1：标准断言
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s := i.(string)
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// 方式2：带检查
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s, ok := i.(string)
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if !ok {
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fmt.Println("类型断言失败")
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}
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```
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### 类型选择
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```go
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func printValue(v interface{}) {
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switch v.(type) {
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case int:
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fmt.Println("整数:", v)
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case string:
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fmt.Println("字符串:", v)
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default:
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fmt.Println("未知类型")
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}
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}
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```
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### 重要提示
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- Go使用组合而非继承
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- 结构体嵌入可以实现类似继承的效果
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- 类型断言若失败会panic，需谨慎使用
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- 类型选择用于处理多种类型
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## 学习目标
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完成本练习后，你将：
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- ✅ 掌握结构体嵌入的使用
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- ✅ 理解接口嵌入的概念
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- ✅ 学会使用类型断言
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- ✅ 掌握类型选择的使用
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## 练习说明
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打开 `main.go`，根据注释提示填充代码，完成后运行 `go test -v` 验证答案。
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