包含头文件和源文件的部分和完整模板专业化(Partial and full template specialization with header and source files)

有人可以帮助我重构下面的代码，以便它编译（使用pre-C ++ 11编译器）。

MyClass.h：

namespace myns { enum LiteralTypes { kINT_LITERAL = 0, kSTRING_LITERAL }; class MyClass { template <LiteralTypes literal_type, typename T> struct AddLiterals; template <typename T> struct AddLiterals<kINT_LITERAL, T> { static void apply(const vector<T>& vals); }; template <> struct AddLiterals<kSTRING_LITERAL, char*> { static void apply(const vector<char*>& vals); }; template <> struct AddLiterals<kSTRING_LITERAL, std::string> { static void apply(const vector<std::string>& vals); }; }; }

MyClass.cpp

namespace myns { template <typename T> void MyClass::AddLiterals<kINT_LITERAL, T>::apply(const vector<T>& vals) { BOOST_STATIC_ASSERT((boost::is_same<T, int16_t>::value || boost::is_same<T, int32_t>::value || boost::is_same<T, int64_t>::value)); // Implementation } template <> void MyClass::AddLiterals<kINT_LITERAL, char*>::apply(const vector<char*>& vals) { // Implementation } template <> void MyClass::AddLiterals<kINT_LITERAL, std::string>::apply(const vector<std::string>& vals) { // Implementation } }

我相信编译错误是因为必须在命名空间范围内定义完全特化，而不是在类定义内部定义。除此之外，我迷路了。

编辑：错误消息（大致）如下：

MyClass.h: error: explicit specialization in non-namespace scope ‘class myns::MyClass’ MyClass.cpp: error: template-id ‘apply<>’ for ‘void myns::MyClass::AddLiterals<kSTRING_LITERAL, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >::apply(const vector<std::string>& vals)’ does not match any template declaration MyClass.cpp: error: invalid function declaration

Could someone please help me refactor the following code so that it compiles (with a pre-C++11 compiler).

MyClass.h:

namespace myns { enum LiteralTypes { kINT_LITERAL = 0, kSTRING_LITERAL }; class MyClass { template <LiteralTypes literal_type, typename T> struct AddLiterals; template <typename T> struct AddLiterals<kINT_LITERAL, T> { static void apply(const vector<T>& vals); }; template <> struct AddLiterals<kSTRING_LITERAL, char*> { static void apply(const vector<char*>& vals); }; template <> struct AddLiterals<kSTRING_LITERAL, std::string> { static void apply(const vector<std::string>& vals); }; }; }

MyClass.cpp

namespace myns { template <typename T> void MyClass::AddLiterals<kINT_LITERAL, T>::apply(const vector<T>& vals) { BOOST_STATIC_ASSERT((boost::is_same<T, int16_t>::value || boost::is_same<T, int32_t>::value || boost::is_same<T, int64_t>::value)); // Implementation } template <> void MyClass::AddLiterals<kINT_LITERAL, char*>::apply(const vector<char*>& vals) { // Implementation } template <> void MyClass::AddLiterals<kINT_LITERAL, std::string>::apply(const vector<std::string>& vals) { // Implementation } }

I believe the compilation error is because full specialization has to be defined at namespace scope, rather than inside the class definition. Beyond this I am lost.

EDIT: The error message is (roughly) as follows:

MyClass.h: error: explicit specialization in non-namespace scope ‘class myns::MyClass’ MyClass.cpp: error: template-id ‘apply<>’ for ‘void myns::MyClass::AddLiterals<kSTRING_LITERAL, std::basic_string<char, std::char_traits<char>, std::allocator<char> > >::apply(const vector<std::string>& vals)’ does not match any template declaration MyClass.cpp: error: invalid function declaration

最满意答案

首先，你在错误信息中有答案：明确的专门化必须在命名空间范围内：

把你的标题变成这样：

namespace myns { enum LiteralTypes { kINT_LITERAL = 0, kSTRING_LITERAL }; class MyClass { template <LiteralTypes literal_type, typename T> struct AddLiterals; }; template <typename T> struct MyClass::AddLiterals<kINT_LITERAL, T> { static void apply(const vector<T>& vals); }; template <> struct MyClass::AddLiterals<kSTRING_LITERAL, char*> { static void apply(const vector<char*>& vals); }; template <> struct MyClass::AddLiterals<kSTRING_LITERAL, std::string> { static void apply(const vector<std::string>& vals); }; }

其次，你有一个不匹配的地方，请注意，你在声明中使用了2d和3d专业化的kSTRING_LITERAL，但是定义了kINT_LITERAL

第三， template<>不用于专业化的成员，所以在cpp文件中省略它

The following worked for me:

MyClass.h:

namespace myns { enum LiteralTypes { kINT_LITERAL = 0, kSTRING_LITERAL }; class MyClass { template <LiteralTypes literal_type, typename T> struct AddLiterals; template <typename T> struct AddLiterals<kINT_LITERAL, T> { static void apply(const vector<T>& vals); }; template <typename T> struct AddLiterals<kSTRING_LITERAL, T> { static void apply(const vector<T>& vals); }; }; }

MyClass.cpp

namespace myns { template <typename T> void MyClass::AddLiterals<kINT_LITERAL, T>::apply(const vector<T>& vals) { BOOST_STATIC_ASSERT((boost::is_same<T, int16_t>::value || boost::is_same<T, int32_t>::value || boost::is_same<T, int64_t>::value)); // Implementation } template <> void MyClass::AddLiterals<kSTRING_LITERAL, char*>::apply(const vector<char*>& vals) { // Implementation } template <> void MyClass::AddLiterals<kSTRING_LITERAL, std::string>::apply(const vector<std::string>& vals) { // Implementation } } // namespace myns

更多推荐