当我尝试在类定义/声明中专门化公共成员函数模板时:
#include <iostream>
class surfaceMesh
{
public:
// Uncomment for Version 0 and 1
class AREA_AVERAGE {};
class ANGLE_AVERAGE {};
template<class Average>
void vertexNormals() {}
// Uncomment: Version 0
//template<>
//void vertexNormals<AREA_AVERAGE> ()
//{
//std::cout << "AREA_AVERAGE" << std::endl;
//}
//template<>
//void vertexNormals<ANGLE_AVERAGE> ()
//{
//std::cout << "ANGLE_AVERAGE" << std::endl;
//}
};
// Uncommend for version 1
template<>
void surfaceMesh::vertexNormals<surfaceMesh::AREA_AVERAGE> ()
{
std::cout << "AREA_AVERAGE" << std::endl;
};
template<>
void surfaceMesh::vertexNormals<surfaceMesh::ANGLE_AVERAGE> ()
{
std::cout << "ANGLE_AVERAGE" << std::endl;
};
int main()
{
surfaceMesh m;
m.vertexNormals<surfaceMesh::AREA_AVERAGE>();
m.vertexNormals<surfaceMesh::ANGLE_AVERAGE>();
return 0;
}
对于版本 0,错误是:
main.cpp:19: error: template-id ‘vertexNormals<mesh::AREA_AVERAGE>’ in declaration of primary template
main.cpp:24: error: explicit specialization in non-namespace scope ‘class mesh’
main.cpp:25: error: template-id ‘vertexNormals<mesh::ANGLE_AVERAGE>’ in declaration of primary template
main.cpp:25: error: ‘void mesh::vertexNormals()’ cannot be overloaded
main.cpp:19: error: with ‘void mesh::vertexNormals()’
版本 1 编译并运行。当然,通常我将类声明和定义分开,但我真的很想知道为什么会发生这种情况。
另外,这是专门化接口的好方法吗?另一种选择是重载函数vertexNormals以获取AREA_AVERAGE或ANGLE_AVERAGE的对象,但这只是一种告诉我将使用哪种函数的类型,它不应该被实例化,所以使用模板'感觉'就像一个正确的选择。