Use golang to convert interfaces and structures

In Go language, assertions can be used to complete interface conversion and structure conversion. Interface conversion includes type assertions and value assertions, which are used to convert values ​​from one interface type to another interface type. Structure conversion is used to convert one structure into another structure.

Use assertions in Go to implement conversion of interfaces and structures

The interface in Go is a collection of methods that allow Different underlying types of values ​​implement them. Interface conversion allows you to convert a value from one interface type to another interface type.

A structure is a collection of related data fields. Sometimes you may want to convert one structure into another. This can be done using assertions.

Interface Conversion

To convert a value from one interface type to another, you can use assertions. Assertions come in two forms:

• Type assertion: This assertion checks whether a value implements a specific interface type.
• Value Assertion: This assertion casts a value to a specific interface type, even if it does not implement that interface.

The following example demonstrates how to use type assertions:

package main

import "fmt"

type Animal interface {
    Speak() string
}

type Dog struct {}
func (d Dog) Speak() string { return "Woof!" }

type Cat struct {}
func (c Cat) Speak() string { return "Meow!"}

func main() {
    var animals []Animal
    animals = append(animals, Dog{}, Cat{})

    for _, animal := range animals {
        if dog, ok := animal.(Dog); ok {
            fmt.Println("Dog says:", dog.Speak())
        } else if cat, ok := animal.(Cat); ok {
            fmt.Println("Cat says:", cat.Speak())
        }
    }
}

Structure conversion

To convert one structure to another, you can Use assertions. The following example demonstrates how to use assertions:

package main

import "fmt"

type User struct {
    Name string
}

type Employee struct {
    User
    Salary int
}

func main() {
    user := User{"Alice"}
    employee := Employee{User{"Bob"}, 1000}

    // 使用断言将 User 转换为 Employee
    if employee, ok := user.(Employee); ok {
        fmt.Println("Employee:", employee.Name, employee.Salary)
    }

    // 使用断言将 Employee 转换为 User
    if user, ok := employee.User.(User); ok {
        fmt.Println("User:", user.Name)
    }
}

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