C++, class as parameter to a method, not template

Question

So, I came across an interesting method signature that I don't quite understand, it went along the lines of:

void Initialize(std::vector< std::string > & param1, class SomeClassName * p);

what I don't understand is the "class" keyword being used as the parameter, why is it there? Is it necessary to specify or it is purely superficial?

Answer 1

It is a forward declaration of the class. It is the effectively the same as

class SomeClassName;
void Initialize(std::vector< std::string > & param1, SomeClassName * p);

There are many situations in which a forward declaration is useful; there's a whole list of things that you can and can't do with a forward declaration in this answer to another question).