How is delayed calling implemented in golang functions?

Delayed function calling in Golang is implemented by the defer keyword, which delays function calling until the current function exits. By adding a defer function to the stack, the function and parameters of the delayed call are stored, ensuring that the delayed function is called only after exiting the function. This is used for asynchronous programming, such as closing a database connection after a function exits. defer can also be used for other purposes such as recording execution time, cleaning up temporary resources, and restoring execution status.

Implementation of delayed function calling in Golang

In Golang, delayed function calling is an asynchronous programming technology that allows us Perform some action after the function exits. This can be achieved by using the defer keyword. The

defer statement delays the execution of a function call until the current function exits. For example, the following code will print "World" when function foo exits:

func foo() {
    defer fmt.Println("World")
    fmt.Println("Hello")
}

Output:

Hello
World

Implementation details

defer How does the statement implement delayed calling in Golang? The

defer statement actually adds an extra function to the call stack, called the defer function. The defer function holds the deferred function and the parameters to be passed to the function.

When the current function exits, it will execute all defer functions on the stack, starting from the first one added. This ensures that deferred functions are not called until the function exits.

Practical case

Consider the following code, which uses defer to close the database connection:

func openDB() (*sql.DB, error) {
    db, err := sql.Open("postgres", "user:password@host:port/dbname")
    if err != nil {
        return nil, err
    }
    defer db.Close() // 数据库连接在函数退出时关闭
    return db, nil
}

This ensures the database connection It will be closed correctly in any case, even if an error occurs during execution.

Other usage

defer can also be used for other purposes, such as:

• Record function execution time
• Clean up temporary resources
• Restore execution state

The above is the detailed content of How is delayed calling implemented in golang functions?. For more information, please follow other related articles on the PHP Chinese website!