Hi,

Update from comment:

I need to extend linq-to-sql classes by own parameters and dont want to touch any generated classes. Any better suggestes are welcome. But I also don't want to do all attributes assignments all time again if the linq-to-sql classes are changing. so if vstudio generates new attribute to a class i have my own extended attributes kept separate, and the new innerited from the class itself

Original question:

i'm not sure if it's possible. I have a class car and a class mycar extended from class car. Class mycar has also a string list. Only difference.

How can i cast now any car object to a mycar object without assigning all attributes each by hand. Like:

Car car = new Car();

MyCar mcar = (MyCar) car;

or

MyCar mcar = new MyCar(car);

or however i can extend car with own variables and don't have to do always

Car car = new Car();
MyCar mcar = new MyCar();
mcar.name = car.name;
mcar.xyz = car.xyz;
...

Thanks.