Template definitions outside class body

Question

Is it O.K. to define virtual function of class template outside its body? Virtual function can not be inlined, but to avoid multiple definitions in compilation units they sh

Answer 1

Yes, it's OK even without inline. It works the same for ordinary member functions and static variables:

// everything in the header:
template 
class A
{
  static int i;
};

template 
int A::i=0;

Standard quote: (3.2/5)

There can be more than one definition of a class type (Clause 9), enumeration type (7.2), inline function with external linkage (7.1.2), class template (Clause 14), non-static function template (14.5.6), static data member of a class template (14.5.1.3), member function of a class template (14.5.1.1), or template specialization for which some template parameters are not specified (14.7, 14.5.5) in a program provided that each definition appears in a different translation unit, and provided the definitions satisfy the following requirements ...

The requirements basically say the two definitions have to be identical.

It doesn't work in case of regular classes. There has to be at most one definition in the whole program.