How to make static Variables in Template classes

[Nils]

Hi,
Ich have a template class and want to initialize a static variable, that is
available for all objekts of the template class, doesn't matter what
template parameter is used.
Can someone please tell me how it will work!

Thanks a lot!
Nils

 

[Victor Bazarov]

Ich have a template class and want to initialize a static variable, that is
available for all objekts of the template class, doesn't matter what
template parameter is used.

You mean, like this:

template<class T> struct NilsClass {
static int someStaticVar;
};

// definition of the static member of the template
template<class T> int NilsClass<T>::someStaticVar = 42;

#include <iostream>
int main() {
NilsClass<double> d;
std::cout << d.someStaticVar << std::endl;
NilsClass<std:stream> dd;
std::cout << dd.someStaticVar << std::endl;
}

Victor

 

[Nils]

Yes, thanks a lot.

You mean, like this:

template<class T> struct NilsClass {
static int someStaticVar;
};

// definition of the static member of the template
template<class T> int NilsClass<T>::someStaticVar = 42;

#include <iostream>
int main() {
NilsClass<double> d;
std::cout << d.someStaticVar << std::endl;
NilsClass<std:stream> dd;
std::cout << dd.someStaticVar << std::endl;
}

Victor

 

[Nicholas Hounsome]

Yes, thanks a lot.

Nils / Victor - I think there may be a misunderstanding - in the above
d.someStaticVar is not the same as dd.someStaticVar

If you want the same var for all template instantiations as Nils originally
stated then you put the static in a non-template class and have the template
class derive from that.