为了简化我负责测试的代码的测试，我正在重构我团队的LogHandler。

他们有这样的事情:

type LogHandlerSt struct {
    path        string
    fileName    string
    projectName string
}

var (
    //Instance The project instance of log handler.
    Instance LogHandlerSt
    //OnResponseError A function that can be set to be called on response error.
    OnResponseError func(context interface{}, response *http.Response)
    //includeStack Will include all lines with the strings below in the debug stack.
    includeStack = []string{"apiserver_sdk", "ezdineserver_sdk"}
)

//CreateLogHandler Creates and assigns a log handler instance for use by the project.
func CreateLogHandler(path string, fileName string, projectName string) LogHandlerSt {
    Instance = LogHandlerSt{path: path, fileName: fileName, projectName: projectName}.
        fmt.Println("Log files are in \"" + path + "\"")
    return Instance
}

//log Logs a message given the type of message and the message itself.
func (handler *LogHandlerSt) log(logType string, errMsg string) {
    fmt.Println(errMsg)
    logFile, err := os.OpenFile(handler.path+"/"+handler.fileName+" "+time.Now().Format("2006-01-02")+".log", os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0777)
    if err != nil {
        fmt.Println(err)
    }
    defer logFile.Close()
    if _, err = logFile.WriteString(`
` + logType + " " + time.Now().Format("2006-01-02 15:04:05.000") + `: ` + errMsg + "\n"); err != nil {
        fmt.Println(err)
    }
    logFile.Sync()
}

//GetProjectNames Gets the projects to use for the log handler instance. Usually used for the debug stack.
func (handler *LogHandlerSt) GetProjectNames() []string {
    var projectNames = []string{handler.projectName}
    projectNames = append(projectNames, includeStack...)
    return projectNames
}

//LogError Logs an error given information.
func (handler *LogHandlerSt) LogError(errMsg string) {
    handler.log("Error", errMsg)
}

//LogWarning Logs a warning given information.
func (handler *LogHandlerSt) LogWarning(errMsg string) {
    handler.log("Warn", errMsg)
}

//LogInfo Logs some information.
func (handler *LogHandlerSt) LogInfo(errMsg string) {
    handler.log("Info", errMsg)
}

被测代码库中的许多方法都在 Instance 上使用这些函数。为了解决这个问题，我引入了一个结构 Logger :

// Logger provides a generic implementation of the required methods.
//  Provided for testing purposes
type Logger interface {
    LogError(errMessage string)
    LogWarning(errMessage string)
    LogInfo(errMessage string)
}

直觉，尤其是来自 Java 的直觉，告诉我将 Instance 的声明更改为 Logger。当然，这什么也没做，因为 Logger 是一个实例，而方法在 *Logger 上。因此，我更改为 Instance *Logger 并重构了 CreateLogHandler 以处理我刚刚创建的编译时错误:

//CreateLogHandler Creates and assigns a log handler instance for use by the project.
func CreateLogHandler(path string, fileName string, projectName string) LogHandlerSt {
    Instance = &LogHandlerSt{path: path, fileName: fileName, projectName: projectName}
        fmt.Println("Log files are in \"" + path + "\"")
    return Instance
}

我被告知:

cannot use LogHandlerSt literal (type *LogHandlerSt) as type *Logger in assignment:
*Logger is pointer to interface, not interface

为什么不，我该怎么办？

最佳答案

" as Logger was an instance whereas the methods were on a *Logger".

停在那里。 Logger 是一个接口(interface)。方法“不在接口(interface)上”。具体的实现有一个具体的接收者类型，它将是*LogHandlerSt，而不是*Logger，也不是Logger。此外 LogHandlerSt 没有实现 Logger，只有 *LogHandlerSt 因为方法是用指针接收器定义的。

如果您引入Logger，您可能会这样使用它:

var Instance Logger

func CreateLogHandler(path string, fileName string, projectName string) Logger {
    Instance = &LogHandlerSt{
        path: path,
        fileName: fileName,
        projectName: projectName
    }
    fmt.Println("Log files are in \"" + path + "\"")
    return Instance
}

因为只有 *LogHandlerSt 实现了 Logger，所以你必须分配一个指向 Instance 的指针。

请注意，您应该很少(如果有的话)使用指向接口(interface)的指针(例如 *Logger)。相反，指向具体类型的指针应该包装在接口(interface)值中。

关于go - 试图将文字转换为 Golang 中的指针，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/51898395/