3

我正在调整现有库（“Webduino”，Arduino 的网络服务器）以与另一个现有库（“WiFly”，wifi 模块）一起使用并遇到问题。每个库都可以独立运行。Webduino 库希望通过 SPI 使用以太网硬件模块，而 WiFi 模块使用串行端口 (UART)。我得到的错误是：

WiFlyClient.h: In member function 'WiFlyClient& WiFlyClient::operator=(const WiFlyClient&)':
WiFlyClient.h:14:
error: non-static reference member 'WiFlyDevice& WiFlyClient::_WiFly', can't use default assignment operator
WiFlyWebServer.h: In member function 'void WebServer::processConnection(char*, int*)':
WiFlyWebServer.h:492: note: synthesized method 'WiFlyClient& WiFlyClient::operator=(const WiFlyClient&)' first required here

以下是相关的代码片段。请注意，到目前为止，我只修改了 WiFlyWebServer.h (Webduino)：

// WiFlyWebServer.h (Webduino)
...
WiFlyServer m_server; // formerly EthernetServer and
WiFlyClient m_client; // EthernetClient
...
void WebServer::processConnection(char *buff, int *bufflen){
  ...
  // line 492
  m_client = m_server.available();
  ...
}



// WiFlyClient.h
class WiFlyClient : public Client {
 public:
  WiFlyClient();
  ...
private:
  WiFlyDevice& _WiFly;
  ...
}



// WiFlyClient.cpp
#include "WiFly.h"
#include "WiFlyClient.h"

WiFlyClient::WiFlyClient() :
  _WiFly (WiFly) {    // sets _wiFly to WiFly, which is an extern for WiFlyDevice (WiFly.h)
  ...
}


// WiFly.h
#include "WiFlyDevice.h"
...
extern WiFlyDevice WiFly;
...



// WiFlyDevice.h
class WiFlyDevice {
  public:
    WiFlyDevice(SpiUartDevice& theUart);
...



// WiFlyDevice.cpp
WiFlyDevice::WiFlyDevice(SpiUartDevice& theUart) : SPIuart (theUart) {
  /*

    Note: Supplied UART should/need not have been initialised first.

   */
  ...
}

问题源于m_client = m_server.available();，如果我评论说问题消失了（但整个事情都依赖于那条线）。实际的问题似乎是 _WiFly 成员在分配 WiFiClient 对象时无法初始化（覆盖？），但我不明白为什么它在没有修改的情况下在这里不起作用。

（是的，我知道头文件中有实现，我不知道他们为什么这样写，不要怪我！）

有什么见解吗？

4

3 回答 3

5

您的WiFly成员WiFlyClient正在使课程不可分配。原因是赋值不能用于更改引用所指的对象。例如：

int a = 1;
int b = 2;
int &ar = a;
int &br = b;
ar = br; // changes a's value to 2, does not change ar to reference b

由于您的所有WiFlyClients 都引用同一个WiFlyDevice实例，因此您可以WiFlyClient按照编译器的建议进行更改以使用静态成员：

// WiFlyClient.h
class WiFlyClient : public Client {
 public:
  WiFlyClient();
  ...
private:
  static WiFlyDevice& _WiFly;
  ...
};

然后，您不在构造函数中初始化它，而是在定义它的源文件中初始化它。

WiFlyDevice & WiFlyClient::_WiFly = WiFly;
于 2012-08-17T20:23:07.603 回答
0

显然，问题是WiFlyClient不可分配的。考虑将它包含在std::unique_ptr（在 C++03 中，std::auto_ptr）中，以便您至少可以分配该类型的项目。

std::unique_ptr<WiFlyClient> m_client;

...

m_client = m_server.available();

...

// convert m_client.<...> to m_client-><...>

// change m_server.available() to return std::unique_ptr<WiFlyClient>
于 2012-08-17T20:04:24.290 回答
0

尝试覆盖operator=：

WiFlyClient& operator= (const WiFlyClient & wi)
{
  /* make a copy here */ 
  return *this;
}
于 2012-08-17T20:26:16.550 回答