“未定义参考”到从静态方法访问的模板类的静态成员 [英] "undefined reference" to static member of template class accessed from static method

问题描述

我有一个静态类方法，需要访问一个指针MyTypePointer，因此必须声明为静态。因为它是一个模板类，我必须将方法放在头文件中，但我不能在头中定义MyTypePointer。

所以我得到未定义的引用错误，因为MyTypePointer未声明。我如何使这工作/声明MyTypePointer。

  myclass.h 
 
 template< typename A，typename B> 
 class PathfindingClass {
 typedef std :: vector< GenericEdgeClass< A，B> *> MyType; 
 static MyType * MyTypePointer; 
}; 
 
 template< typename A，B> 
 void MyClass< A，B> :: MyMethod（int x，int y）{
 //使用MyTypePointer执行某些操作
} 
  pre> 
 
 
非常感谢。
解决方案
 ， static MyType * MyTypePointer;  声明一个对象。您仍然必须在模板类定义之外定义：
  template< class A， B类> 
 typename PathfindingClass< A，B> :: MyType * 
 PathfindingClass< A，B> :: MyTypePointer; 
  
 
I have a static class method that needs access to a pointer MyTypePointer that therefore has to be declared static. Since it is a template class I have to put the methods inside the header file but I can't define MyTypePointer in the header. 

So I get the "undefined Reference" error since MyTypePointer is not declared. How can I make this work / declare MyTypePointer. 
myclass.h

template <typename A, typename B>
class PathfindingClass {
    typedef std::vector<GenericEdgeClass<A, B>*> MyType;
    static MyType *MyTypePointer;
};

template <typename A, B>
void MyClass<A, B>::MyMethod(int x, int y) { 
    //do something with MyTypePointer
}
Thank you very much.
解决方案
In the template definition, static MyType *MyTypePointer; declares an object. You still have to define it, outside the template class definition:
template <class A, class B>
typename PathfindingClass<A, B>::MyType*
PathfindingClass<A, B>::MyTypePointer;


                        
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