Question

I use Linq-to-SQL which will generate classes for database tables dragged to its designer. When I drag Product table to designer, Visual Studio will generate like this:

[global::System.Data.Linq.Mapping.TableAttribute(Name="dbo.Products")]
public partial class Product : INotifyPropertyChanging, INotifyPropertyChanged
{
    // ...
    partial void OnProductIDChanging(int value);
    partial void OnProductIDChanged();

    [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_ProductID", AutoSync=AutoSync.OnInsert, DbType="Int NOT NULL IDENTITY", IsPrimaryKey=true, IsDbGenerated=true)]
    public int ProductID
    {
        get
        {
            return this._ProductID;
        }
        set
        {
            if ((this._ProductID != value))
            {
                this.OnProductIDChanging(value);
                this.SendPropertyChanging();
                this._ProductID = value;
                this.SendPropertyChanged("ProductID");
                this.OnProductIDChanged();
            }
        }
    }
     //...
}

OnProductIDChanging and OnProductIDChanged are not abstract methods and they are empty but why they don’t give compiling-error. Thanks.

Answer 1

Because they are partial methods.

This article has a very good explanation of partial methods.