具有默认值的构造函数对象参数？

Question

我的 Singleton 类有一个像这样的构造函数：private LanDataEchangeWCF_Wrapper( // ILanDataEchangeWCFCallback callbackReciever ,// No error    ILanDataEchangeWCFCallback callbackReciever = new LanCallBackDefaultHandler(), // Error    bool cleanExistingConnection = true,    bool requirePingToKeepAlive = true,    int pingFrequency = 30000){    if (cleanExistingConnection)    {        ExistingConnectionCleaner();    }    InitWs(callbackReciever);    if (requirePingToKeepAlive)    {        timer = new Timer(pingFrequency);        timer.Enabled = true;        timer.Elapsed += KeepAlive;    }}随着LanCallBackDefaultHandler接口的实现ILanDataEchangeWCFCallbackclass LanCallBackDefaultHandler : ILanDataEchangeWCFCallback{    public void WakeUP(int newID, string entity)    {        throw new NotImplementedException();    }}我希望能够在LanDataEchangeWCF_Wrapper()不实现以下重载的情况下调用，这将是 99% 的代码重复：private LanDataEchangeWCF_Wrapper(    bool cleanExistingConnection = true,    bool requirePingToKeepAlive = true,    int pingFrequency = 30000){    if (cleanExistingConnection)    {        ExistingConnectionCleaner();    }    InitWs(new LanCallBackDefaultHandler());    if (requirePingToKeepAlive)    {        timer = new Timer(pingFrequency);        timer.Enabled = true;        timer.Elapsed += KeepAlive;    }}当我试图弄清楚如何去做时，我遇到的最后一个错误是默认参数需要是编译时常量使用构造函数，我不能做一些简单的函数重载之类的事情，这将删除代码重复：private object Methode() {    return new Methode(new LanCallBackDefaultHandler());}private object Methode(ILanDataEchangeWCFCallback callbackReciever){    //Do things    return ;}如何获得对象的编译时常量新实例？

Answer 1

我通常做的是分配一个默认值 null 然后检查它是否为 null 并将其分配给一个新对象。类似于下面。

private LanDataEchangeWCF_Wrapper(

    ILanDataEchangeWCFCallback callbackReciever = null,

    bool cleanExistingConnection = true,

    bool requirePingToKeepAlive = true,

    int pingFrequency = 30000)

{

    callbackReciever = callbackReciever ?? new LanCallBackDefaultHandler();

    //Rest of constructor

}

Answer 2

构造函数重载 ?

private LanDataEchangeWCF_Wrapper(bool cleanExistingConnection = true, 

                                  bool requirePingToKeepAlive = true, 

                                  int pingFrequency = 30000)

: this (new LanCallBackDefaultHandler(), 

        cleanExistingConnection, 

        requirePingToKeepAlive, 

        pingFrequency) {}

private LanDataEchangeWCF_Wrapper(ILanDataEchangeWCFCallback callbackReciever,

                                  bool cleanExistingConnection = true,

                                  bool requirePingToKeepAlive = true,

                                  int pingFrequency = 30000)

{

    if (cleanExistingConnection)

    {

        ExistingConnectionCleaner();

    }

    InitWs(callbackReciever);

    if (requirePingToKeepAlive)

    {

        timer = new Timer(pingFrequency);

        timer.Enabled = true;

        timer.Elapsed += KeepAlive;

    }

}