Question

我有以下代码：

bool SendClientRequest(Action<ICustomerService> channel)
{

  string proxy ="my.proxy.domain:8080";
  string user = "user1";
  string password="secret";

  // maybe i do not need this 3 lines!
  WebProxy webproxy = new WebProxy(proxy, true);
  webproxy.Credentials = new NetworkCredential(user, password);
  WebRequest.DefaultWebProxy = webproxy;

  CustomBinding customBinding = new CustomBinding();
  customBinding.Elements.Add(new HttpTransportBindingElement()
  {

   AuthenticationSchemes.None : AuthenticationSchemes.Basic,                
   ProxyAddress = string.IsNullOrEmpty(proxy) ? null : new Uri(proxy),
   UseDefaultWebProxy = false,
   BypassProxyOnLocal = true,
   TransferMode = TransferMode.Streamed,
   MaxReceivedMessageSize = 84087406592,
   MaxBufferPoolSize = 0x1000000,
   MaxBufferSize = 0x1000000

  });


  using (ChannelFactory<ICustomerService> factory = new  
  ChannelFactory<ICustomerService>(customBinding ))
  {
   IClientChannel contextChannel = null;
   string url = "http://my.domain.de/Distribution/eService.svc", 
   EndpointAddress ep = new EndpointAddress(url);
   ICustomerService clientChannel = factory.CreateChannel(ep);                


   contextChannel = clientChannel as IClientChannel;
   contextChannel.OperationTimeout = TimeSpan.FromMinutes(rcvTimeout );

   channel(clientChannel); // <- here i get the exception!
   return true;
  }
}

到目前为止一直很好，但我在以下代码中遇到错误Class A { public: A::A(const char* name): _name(name) {} virtual void doSomething(); private: const char* _name; } Class B : public A { B::B(const char* name): A(name) {} void doSomething() { //do something } }：

crosses initialization of B* newB

为什么会出错？

一些背景：我想在向量中存储派生类的指针，以便于搜索/迭代。名称是唯一的，因此我可以遍历向量并查找指向具有正确名称的对象的指针。从指向对象调用方法时，应该调用继承的方法（std::vector<A*> vectorOfAs; switch (enumType) { case enum1 : B* newB = new B("foobar"); vectorOfAs.push_back(newB); break; case enum2 : C* newC = new C("barfoo"); vectorOfAs.push_back(newC); break; }）。

编辑：@FrançoisAndrieux：你是对的。做了（严重的）错字。已将//do something更改为Class B : public B

Answer 1

newB在switch语句的范围内，这使得它在所有交换机情况下都可用，但不会在所有这些情况下初始化。您应将每个案例放在其自己的本地范围内（有关详细信息，请参阅this answer）：

switch (enumType) {
  case enum1 : 
  {
    B* newB = new B("foobar");
    vectorOfAs.push_back(newB);
    break;
  }
  case enum2 :
  {
    C* newC = new C("barfoo");
    vectorOfAs.push_back(newB);
    break;
  }
}

此时你会在enum2中遇到一个编译器错误（从而暴露出一个错误），因为你推动newB而不是newC，这就是我认为你想要的：

switch (enumType) {
  case enum1 : 
  {
    B* newB = new B("foobar");
    vectorOfAs.push_back(newB);
    break;
  }
  case enum2 :
  {
    C* newC = new C("barfoo");
    vectorOfAs.push_back(newC); // <--
    break;
  }
}

这应该有用。

在switch case语句中交叉初始化错误

1 个答案: