类构造函数构造函数 className 或 className.identifier, 关键字 new 可选.构造函数语句执行顺序:初始化器,父类构造函数,子类构造函数。class Point { num x, y, distance; /* 1,匿名构造函数 ......
Improved readability: With using, the new name comes first rather than being embedded somewhere in a declaration. Generality: using can be used for template ali...