Default object implementation

I want to implement default object pattern for my all classes in the inheritance tree. I am doing as shown below.

 namespace test
{
    public class Record
    {
        pu开发者_如何学JAVAblic int ID { get; set; }
    }

    public class StudentRecord : Record
    {
        public string StudentID { get; set; }
    }

    public class DriverRecord : Record
    {
        public string DLNumber { get; set; }
    }

    public class client
    {
        public static void Main()
        {
            StudentRecord st = StudentRecord.Default;
            DriverRecord dr = DriverRecord.Default;
        }
    }
}

I want the default property or method to initialize all the class level properties to their defaults and I don’t want to repeat the implementation for each class. I just want to write on Record (base ) class . Can you provide some suggestions on this?

What you’re looking for is exactly what constructors are for. A constructor can call an inherited base constructor, so you need to do the base initialisation in only one place. Sometimes the basic functionality really does what you need :)

public class Record
{
    public int ID { get; set; }
    public Record()
    {
        // ... do general initialisation here ...
    }
}

public class StudentRecord : Record
{
    public string StudentID { get; set; }
    public StudentRecord()
        : base()    // This calls the inherited Record constructor,
                    // so it does all the general initialisation
    {
        // ... do initialisations specific to StudentRecord here ...
    }
}

public class client
{
    public static void Main()
    {
        // This calls the constructor for StudentRecord, which
        // in turn calls the constructor for Record.
        StudentRecord st = new StudentRecord();
    }
}

The Record class can only set the properties which are inherited by StudentRecord and DriverRecord. If you want to set class-specific properties to their default values you have to override the method (I would make a method) and do something like this (for StudentRecord ):

public void override Initialize()
{
    base.Reset();

    this.StudentId = 0;
}

HTH

You don't have any "class level properties", i.e. static properties, in your code sample. The properties you do have (the instance properties) are already initialized to their defaults -- 0 for integers, null for references, etc.

If you want to define your own defaults -- perhaps ID should default to -1 until you save, and the strings should default to "" -- then that's exactly what constructors are for:

public class Record
{
    public Record() { ID = -1; }
    public int ID { get; set; }
}
public class StudentRecord : Record
{
    public StudentRecord() { StudentID = ""; }
    public string StudentID { get; set; }
}
// etc.

If you want something different from either of those, you'll have to explain what you're looking for.

I think Null Object Pattern is what you need.