Article about free static function usage

Question

I am looking for an article or documentation that explains why a free static function is better than a private member function, when the given function does not modify or read the private members of the class. To my point of view the advantages are :

• Less dependencies

• Better encapsulation (for "mammoth" classes, it helps to know that at least those function calls do not modify the members)

I am certain someone has already written something better than what I can do.

Answer 1

Free static functions are passe. One would use a function in the anonymous namespace instead.

They are slightly more maintainable -- since they can't access private members, they are robust against changes to implementation details. A static member function could also be independent of implementation details, but you don't have the compiler verifying that.