[Help] A Question About Template Specialization

This is a discussion on [Help] A Question About Template Specialization within the C++ Programming forums, part of the General Programming Boards category; compiled the following code Code: class t { public: template <typename T> void tt(T i) { } template <> void ...

  1. #1
    C/C++Newbie Antigloss's Avatar
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    [Help] A Question About Template Specialization

    compiled the following code
    Code:
    class t {
    public:
       template <typename T>
       void tt(T i) { }
       template <>
       void tt(int i) { }
    };
    
    int main()
    {
    }
    and I got the following error message
    5 invalid explicit specialization before '>' token
    5 explicit specialization in non-namespace scope `class t'
    6 invalid member function declaration
    but if I moved function tt out of the class t, say,
    Code:
    template <typename T>
    void tt(T i) { }
    template <>
    void tt(int i) { }
    
    int main()
    {
    }
    then it compiled well.

    I wonder if C++ dosen't support such kind of specialization inside a class? Why? For any good reason?

    Anyway, I do need to declare a template function, and a special version of this function, inside a normal class. How? The only alternative is to make it an overloaded function? say,
    Code:
    class t {
    public:
       template <typename T>
       void tt(T i) { }
    
       void tt(int i) { }
    };
    
    int main()
    {
    }
    then it compiled well
    Last edited by Antigloss; 10-31-2007 at 08:31 AM.

  2. #2
    Captain Crash brewbuck's Avatar
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    You can't partially specialize a template method, any more than you can a template function.

    Partial specialization is for templates CLASSES only. To specialize functions you just use overloading.

  3. #3
    C/C++Newbie Antigloss's Avatar
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    but as you can see here, this is a complete specialization, not partial.
    Partial specialization is OK for function too.

  4. #4
    C/C++Newbie Antigloss's Avatar
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    finally, i got how to specialize template methods
    Code:
    class t {
    public:
       template <typename T>
       void tt(T i) { }
    };
    
    template <>
    void t::tt(int i) { }
    
    int main()
    {
    }

  5. #5
    Captain Crash brewbuck's Avatar
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    Quote Originally Posted by Antigloss View Post
    but as you can see here, this is a complete specialization, not partial.
    Partial specialization is OK for function too.
    No it is not. Try compiling this:

    Code:
    template <typename A, typename B>
    void func(A a, B b) { }
    
    template <typename B>
    void func<int, B>(int a, B b) { }
    The message my compiler gives is:
    t.cc:5: partial specialization `func<int, B>' of function template
    As I said, you can't partially specialize a function template this way. You have to overload it.

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