Automatic Properties in C# 3 - Must declare a body for get if I declare one for set?

Question

I'm using VS 2008, and in my property pages for the project I see that I'm targeting .Net 3.5.

Here is the error I'm getting when trying to compile:

AMSDataModels.Vehicle.VIN.get' must declare a body because it is not marked abstract, extern, or partial

And here is the code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace AMSDataModels
{
    public class Vehicle
    {
        //NodeID for datastore persistance
        public Guid NodeID { get; set; }

        public string VIN { get; 
            set { 
                if (value.Length != 17) throw new ArgumentOutOfRangeException("VIN", "VIN must be 17 characters"); 
            } }

        public string Make { get; set; }
        public string Model { get; set; }
    }
}

If I strip the body from set so that its just:

public string VIN { get; set; }

All works, but I lose my ability to check the VIN as it is set.

Does anyone have a suggestion of how to fix this or a better way to approach the problem at hand?

I really like the shorthand notation - but verifying the legitimacy of input is important too!

Answer 1

If you're going to add logic in the set, you need to add it into the get as well. Notice in your set you're not actually setting a value to anything?

Add a backing field,

private string _vin;

and return that in the get.

public string VIN
{
    get { return _vin; }
    set
    {
      if (value.Length != 17) 
        throw new ArgumentOutOfRangeException("VIN", "VIN must be 17 characters"); 
      else
        _vin = value;
    }
}