is it a good idea to create an enum for the key names of session values?

Question

instead of doing

 session(\"myvar1\") = something
 session(\"myvar2\") = something
 session(\"myvar3\") = something
 session(\"myvar4\") = something

Answer 1

I've used classes like this to make a typed session/cache wrapper. You may need to add additional code to the get/set, but I'll leave that up to you.

internal class SessionHelper
{
    private const string  myVar1Key = "myvar1";

    public static int MyVar1
    {
        get
        {
            return (int)System.Web.HttpContext.Current.Session[myVar1Key];
        }
        set
        {
            System.Web.HttpContext.Current.Session[myVar1Key] = value;
        }
    }
}

Sorry about the C#....