我正在阅读Vandevoorde和Josuttis的“C模板完整指南”(顺便说一句,这看起来还不错).这个说法(第3.3节)似乎是错误的
and is not in the published errata：
If you specialise a class template,you must also specialise all member functions. Although it is possible to specialise a single member function,once you have done so,you can no longer specialise the whole class.
然而以下编译在gcc上
模板
<typename T>
struct C {
T foo ();
T bar ();
};
template <>
struct C<int> {
int foo ();
int bar () {return 4;}
};
template <typename T>
T C<T> :: foo () {return 0;}
template <typename T>
T C<T> :: bar () {return 1;}
int C<int> :: foo () {return 2;}
template <>
float C<float> :: bar () {return 3;}
#include <cassert>
int main () {
C<int> i;
C<float> f;
assert (2 == i .foo ());
assert (0 == f .foo ());
assert (4 == i .bar ());
assert (3 == f .bar ());
}
我有专门的C< int> :: foo和C< float> :: bar所以教科书错了,gcc超出了标准,还是我误解了整个情况？
谢谢.
解决方法
你不能做这个：
template <typename T> struct C
{
T foo () { return 0;}
T bar () { return 1;}
};
// partial specialization of foo on C<int>
template <>
int C<int> :: foo () {return 2;}
// partial specialization of bar on C<float>
template <>
float C<float> :: bar () {return 3;}
// will not compile,C<int> already partially specialized
template <>
struct C<int>
{
int foo() {return 10;}
int bar() {return 10;}
};
