A class can contain a member template variable which must be static:
class B
{
public:
template <typename X>
static X var;
B() { std::cout << "Create B " << __PRETTY_FUNCTION__ << std::endl; }
template <typename T>
void Print() { std::cout << "Value is " << var<T> << std::endl; }
};
It must as all static members be declared outside the class scope:
The following compiles and works as expected:
template<typename T> T B::var=9; // makes only sense for int,float,double...
But how to specialize such a var like the following non working code ( error messages with gcc 6.1):
template <> double B::var<double>=1.123;
Fails with:
main.cpp:49:23: error: parse error in template argument list
template <> double B::var<double>= 1.123;
^~~~~~~~~~~~~~~~~~
main.cpp:49:23: error: template argument 1 is invalid
main.cpp:49:23: error: template-id 'var<<expression error> >' for 'B::var' does not match any template declaration
main.cpp:38:22: note: candidate is: template<class X> T B::var<T>
static X var;
template <> double B::var=1.123;
Fails with
template <> double B::var=1.123;
^~~
main.cpp:38:22: note: does not match member template declaration here
static X var;
What is the correct syntax here?
I suppose you should add a space
template <> double B::var<double> = 1.123;
^ here
Otherwise (if I'm not wrong) >=1.123
is confused with "equal or greather than 1.123"