请教：template的static member function 该怎么用？

andyY

一个singleton模板实现的练习
Sing.h

1. #include <pthread.h>
   
2. 
   
3. template <class T> class CTplSingleton
   
4. {
   
5. private:
   
6.   static T _instance;
   
7.   static pthread_mutex_t mutex;
   
8. protected:
   
9.   CTplSingleton<T>& operator=(const CTplSingleton<T>&);
   
10.   CTplSingleton();
    
11.   ~CTplSingleton();
    
12. public:
    
13.   static T& instance();
    
14. };

复制代码

Sing.cpp

1. #include "Sing.h"
   
2. 
   
3. //static member data
   
4. template<class T> pthread_mutex_t CTplSingleton<T>::mutex = PTHREAD_MUTEX_INITIALIZER;
   
5. 
   
6. template<class T> T CTplSingleton<T>::_instance;
   
7. 
   
8. //protected member  function
   
9. template <class T> CTplSingleton<T>::CTplSingleton()
   
10. {}
    
11. 
    
12. template <class T> CTplSingleton<T>::~CTplSingleton()
    
13. {}
    
14. 
    
15. template <class T> CTplSingleton<T>& CTplSingleton<T>::operator=(const CTplSingleton<T>&)
    
16. {}
    
17. 
    
18. //public member function
    
19. template <class T> T& CTplSingleton<T>::instance()
    
20. {
    
21.   if( 0 == _instance )
    
22.   {
    
23.     pthread_mutex_lock(&mutex);
    
24.     if( 0 == _instance )
    
25.     {
    
26.       _instance = * new T;
    
27.     }
    
28.     pthread_mutex_unlock(&mutex);
    
29.   }
    
30. 
    
31.   return _instance;
    
32. }

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demo.cpp

1. #include "Sing.h"
   
2. int main()
   
3. {
   
4.   int ref = CTplSingleton<int>::instance();
   
5. }

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g++ demo.cpp Sing.cpp -Wall

demo.cpp: In function `int main()':
demo.cpp:65: warning: unused variable `int ref'
/tmp/ccV1tcJm.o(.text+0x11): In function `main':
: undefined reference to `CTplSingleton<int>::instance()'
collect2: ld returned 1 exit status

[root@VM template]# uname -a
Linux VM 2.4.20-8 #1 Thu Mar 13 17:54:28 EST 2003 i686 i686 i386 GNU/Linux

[root@VM template]# g++ --version
g++ (GCC) 3.2.2 20030222 (Red Hat Linux 3.2.2-5)
Copyright (C) 2002 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

静态成员函数应该怎么用的？

[ 本帖最后由 andyY 于 2006-10-25 13:40 编辑 ]

coldwarm

跟静态成员函数如何使用无关,类模板的成员函数的声明和定义都要放到头文件里,否则你无法在编译时进行模板展开,所以编译器会报告无法找到成员函数.

andyY

哦，汗。谢谢！