c++ template partial specialization member function
Solution 1
You cannot partially specialize only a single member function, you must partially specialize the whole class. Hence you'll need something like:
template <typename T>
class Object<T, 0>
{
private:
T m_t;
Object();
public:
Object(T t): m_t(t) {}
T Get() { return m_t; }
Object& Deform()
{
std::cout << "Spec\n";
m_t = -1;
return *this;
}
};
Solution 2
14.5.5.3.1. The template parameter list of a member of a class template partial specialization shall match the template parameter list of the class template partial specialization. The template argument list of a member of a class template partial specialization shall match the template argument list of the class template partial specialization.
In other words: no partially specialized member without partially specialized class.
Solution 3
Unfortunately, you can't partially specialize member function of a template class. You may either partially specialize the whole class or use inheritance. You may also use both:
template <typename T, int nValue>
class Object {
protected:
T m_t;
public:
Object() = delete;
Object(T t): m_t(t) {}
T Get() { return m_t; }
Object& Deform() {
m_t *= nValue;
return *this;
}
};
template <typename T>
class Object<T,0> : public Object<T,1> {
public:
using Object<T,1>::Object;
Object& Deform() {
this->m_t = -1;
return *this;
}
};
Simon Righley
Updated on February 14, 2020Comments
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Simon Righley over 4 years
I'm new to templates so maybe this is a trivial thing but I cannot get it to work. I'm trying to get partial specialization of a class member function. The shortest code would be:
template <typename T, int nValue> class Object{ private: T m_t; Object(); public: Object(T t): m_t(t) {} T Get() { return m_t; } Object& Deform(){ m_t*=nValue; return *this; } }; template <typename T> Object<T,0>& Object<T,0>::Deform(){ this->m_t = -1; return *this; } int main(){ Object<int,7> nObj(1); nObj.Deform(); std::cout<<nObj.Get(); }
I tried with nonmember functions and that's worked fine. What also works fine is full specialization of a member function.
But, whenever I try with partial spec. of a member function I get error of the form:
PartialSpecification_MemberFu.cpp(17): error: template argument list must match the parameter list Object<T,0>& Object<T,0>::Deform().
Would appreciate any help :-)