[英]Class template method specialization
I'm trying to specialize a template method like this:我正在尝试专门化这样的模板方法:
template <typename X, typename Y>
class A {
public:
void run(){};
};
template<typename Y>
void A<int, Y>::run() {}
But I get但我得到
main.cpp:70:17: error: nested name specifier 'A<int, Y>::' for declaration does not refer into a class, class template or class template partial specialization
I understand that the specialization isn't yet complete because I haven't instantiated it with a specific Y
, but how can I do that?我知道专业化还没有完成,因为我还没有用特定的
Y
实例化它,但是我该怎么做呢?
You need at first partially specialize the class itself including the function declaration.您首先需要部分特化类本身,包括函数声明。 After that you can write its definition.
之后,您可以编写其定义。 You may not partially specialize a function.
您可能不会部分特化某个功能。
For example例如
#include <iostream>
template <typename X, typename Y>
class A {
public:
void run()
{
std::cout << "How do you do?\n";
};
};
template<typename Y>
class A<int, Y>
{
public:
void run();
};
template<typename Y>
void A<int, Y>::run()
{
std::cout << "Hello World!\n";
}
int main()
{
A<int, int>().run();
A<double, int>().run();
return 0;
}
The program output.程序输出。
Hello World!
How do you do?
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