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To instantiate a template function explicitly, follow the template keyword by a declaration (not definition) for the function, with the function identifier followed by the template arguments. template float twice<float>( float original ); Template arguments may be omitted when the compiler can infer them.
You can't really get a high quality template work-alike in C with preprocessor macros; because, those macros expand only once, so at best you can get a data structure that can be retyped, but once processed is that type for the whole program.
Member functions can be function templates in several contexts. All functions of class templates are generic but are not referred to as member templates or member function templates. If these member functions take their own template arguments, they are considered to be member function templates.
Example 1: C++ Class Templates template <class T> class Number { private: T num; public: Number(T n) : num(n) {} T getNum() { return num; } }; Notice that the variable num , the constructor argument n , and the function getNum() are of type T , or have a return type T . That means that they can be of any type.
Your guess is the correct one. The only thing you have to remember is that the member function template definition (in addition to the declaration) should be in the header file, not the cpp, though it does not have to be in the body of the class declaration itself.
See here: Templates, template methods,Member Templates, Member Function Templates
class Vector
{
int array[3];
template <class TVECTOR2>
void eqAdd(TVECTOR2 v2);
};
template <class TVECTOR2>
void Vector::eqAdd(TVECTOR2 a2)
{
for (int i(0); i < 3; ++i) array[i] += a2[i];
}
Yes, template member functions are perfectly legal and useful on numerous occasions.
The only caveat is that template member functions cannot be virtual.
The easiest way is to put the declaration and definition in the same file, but it may cause over-sized excutable file. E.g.
class Foo
{
public:
template <typename T> void some_method(T t) {//...}
}
Also, it is possible to put template definition in the separate files, i.e. to put them in .cpp and .h files. All you need to do is to explicitly include the template instantiation to the .cpp files. E.g.
// .h file
class Foo
{
public:
template <typename T> void some_method(T t);
}
// .cpp file
//...
template <typename T> void Foo::some_method(T t)
{//...}
//...
template void Foo::some_method<int>(int);
template void Foo::some_method<double>(double);
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