c++ - pthread_create 模板函数——静态转换模板类

Question

我不知道是否需要比下面的代码更多的信息，但如果需要更多信息，请直接说明，我将发布剩余的代码。编译时出现以下错误:

g++ -c -pipe -O2 -Wall -W  -I../../../../QtSDK/Desktop/Qt/4.8.0/gcc/mkspecs/linux-g++ -I. -o main.o main.cpp
In file included from main.cpp:4:
TimerManager.h: In function 'void* create_pthread(void*)':
TimerManager.h:17: error: expected nested-name-specifier before 'TimerManager'
TimerManager.h:17: error: expected '(' before 'TimerManager'
TimerManager.h:17: error: expected ';' before 'TimerManager'
make: *** [main.o] Error 1

---

我需要更改以下哪些内容才能消除这些错误？

---

template<class Object>
void *create_pthread(void *data)
{
  typename TimerManager<Object> *tm = static_cast<TimerManager<Object> *>(data);
  return data;
}

...

template<class CallObject>
class TimerManager {
    ...
};

...

template<class CallObject>
TimerManager<CallObject>::TimerManager() :
  m_bRunning(false),
  m_bGo(false),
  m_lMinSleep(0)
{
  int mutex_creation = pthread_mutex_init(&m_tGoLock, NULL);
  if(mutex_creation != 0) {
    throw TimerManager::TimerError(std::string("Failed to create mutex"));
  }

  int mutex_cond_creation = pthread_cond_init(&m_tGoLockCondition, NULL);
  if(mutex_cond_creation != 0) {
    throw TimerManager::TimerError(std::string("Failed to create condition mutex"));
    return;
  }

  int thread_creation = pthread_create(&m_tTimerThread, NULL, create_pthread<CallObject>, this);
  if(thread_creation != 0) {
    throw TimerManager::TimerError(std::string("Failed to create thread"));
    return;
  }
  m_bRunning = true;
}

Answer 1

我认为问题在于，考虑到声明的顺序，TimerManager在定义 create_pthread 之前尚未声明类模板.结果，编译器报错，因为TimerManager不在范围内。重新排序功能应该可以解决这个问题。

此外，您不需要 typename在行中

typename TimerManager<Object> *tm = static_cast<TimerManager<Object> *>(data);

typename仅当您访问 TimerManager<Object> 中的嵌套类型时才有必要.您应该能够毫无问题地删除它。

希望这对您有所帮助!