namedparams.cpp

class my_class
{
public:
	struct args {
		nullable<int> some_int;
		nullable<float> some_float;
	};
	
	template<typename args_func>
	my_class(args_func get_args)
	{
		args a;
		get_args(a);
		
		if (a.some_int.is_valid()) {
			// We should probably do something to default some_int to a real value.
		}
		
		if (a.some_float.is_valid()) {
			// ... same for some_float.
		}
	}
}

// [...]

my_class foo([](auto& a) { 
	a.some_int = 5; 
});