On 1/06/2016 11:48, Emil Dotchevski wrote:
No, I said non-friend. Look, there is no semantic difference between allowing non-friend member functions to be added without changes to the type definition on one hand, and allowing non-friend free functions to be added without changes to the type definition on the other hand. Neither breaks the encapsulation; the difference is entirely syntactic.
This is basically what .NET extension methods do -- they're static functions outside of a class declared with some initial parameter of a particular type. They can be invoked either as static methods passing the parameters exactly as declared, or as if they were member functions where the initial parameter is removed from the argument list and placed before the dot instead. eg. public static int Sum(this IEnumerable<int> list), which can be called just as list.Sum() on any IEnumerable<int>. It's purely syntactic but allows for some highly readable code. (Although it's easy to get carried away sometimes.)