Dynamic creation and destruction mechanism of golang function type

The Go language provides the func type for dynamic creation and destruction of function values: Creation: Use the func keyword to dynamically create a function type, such as f := func(x int) int { return x * x }. Call: Pass a function value as a parameter to another function, such as call(f, 5). Destruction: Function values ​​are destroyed when they go out of scope, similar to variables.

Dynamic creation and destruction mechanism of function types in Go language

Go language provides built-in func type, which allows us Create and use function values.

Dynamic creation of function types

You can use the func keyword to dynamically create a function type:

f := func(x int) int {
    return x * x
}

The above code creates a function type that accepts Takes an integer argument and returns an integer.

Dynamic call function value

You can call a function value by passing it as a parameter to another function:

func call(f func(int) int, x int) {
    fmt.Println(f(x))
}

call(f, 5)

Destroy function value

Function value have the same life cycle as variables, they are destroyed when they go out of scope.

Practical case: dynamically create a callback function

Creating a callback function in a goroutine to process the results is a common scenario:

func main() {
    ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
    defer cancel()

    resultCh := make(chan int)

    // 创建回调函数
    f := func(result int) {
        resultCh <- result
    }

    go func() {
        // 模拟耗时的处理
        time.Sleep(5 * time.Second)
        result := 42
        f(result)
    }()

    select {
    case result := <-resultCh:
        fmt.Println("Received result:", result)
    case <-ctx.Done():
        fmt.Println("Timed out waiting for result")
    }
}

In this example, the dynamically created callback Function f is used to notify the main goroutine of the result after the goroutine completes processing.

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