I have the following classes hierarchy:
abstract class Product : IComparable
{
public string Name { get; set; }
public decimal Price { get; set; }
public string Barcode { get; set; }
public int CompareTo(object obj)
{
int ret = -1;
if (String.Compare(this.GetType().Name, obj.GetType().Name,StringComparison.Ordinal) == 0)
ret = 0;
return ret;
}
}
abstract class Book : Product
{
public int PagesCount { get; set; }
}
class ProgrammingBook : Book
{
public string ProgrammingLanguage { get; set; }
}
class CulinaryBook : Book
{
public string MainIngridient { get; set; }
}
class EsotericBook : Book
{
public int MininumAge { get; set; }
}
abstract class Disc : Product
{
internal enum Content
{
Music,
Video,
Software
}
public Content DiscContent { get; set; }
}
class CdDisc : Disc
{
}
class DvdDisc : Disc
{
}
And I trying to sort following collection by using IComparable interface method CompareTo:
List<Product> products = new List<Product>
{
new DvdDisc {Name = "The lord of the rings 2",DiscContent = Disc.Content.Video,Price = 200M,Barcode = "5435443-2"},
new CdDisc {Name = "Antonio Vivaldi: best picks",Price = 700M, DiscContent = Disc.Content.Music,Barcode = "4543765-565"},
new CulinaryBook{Name = "Midterranian foods",MainIngridient = "Salmon",PagesCount = 436,Price = 350M,Barcode = "41457561-897"},
new CdDisc{Name = "Windows XP", DiscContent = Disc.Content.Software, Price = 950M, Barcode = "5433668-4"},
new EsotericBook{Name = "Russian Freemasonry 1731-2000",MininumAge = 21,PagesCount = 2100,Price = 3000M,Barcode = "6464632-876"},
new CdDisc {Name = "The best of Mussorgsky",Price = 300M, DiscContent = Disc.Content.Music,Barcode = "5435436-567"},
new ProgrammingBook{Name = "CLR via C#",PagesCount = 900, Price = 1110M,ProgrammingLanguage = "C#",Barcode = "5546533-2446"},
new DvdDisc {Name = "The lord of the rings 1",DiscContent = Disc.Content.Video,Price = 200M,Barcode = "54354423-2"},
new ProgrammingBook{Name = "ASP.NET MVC 4",PagesCount = 800,Price = 1200M,ProgrammingLanguage = "C#",Barcode = "46476573-65"},
new EsotericBook{Name = "Russian Freemasonry in it's future and past",MininumAge =19, PagesCount = 900, Price = 2342M,Barcode = "3656353-24"},
new CulinaryBook{Name = "Traditional Polish dishes",MainIngridient = "Red meat",PagesCount = 630,Price = 840,Barcode = "54634234-5"}
}; products.Sort();
Output list should look like this:
1.1 Programming books
1.2 Culinary books
1.3 Esoteric books
2.1 Cd discs sorted by content
2.2 DVD discs sorted by content
My current CompareTo method does only part of the job - comparing classes by name.
This is a working example that will render the exact same output:
1.1 Programming books
1.2 Culinary books
1.3 Esoteric books
2.1 Cd discs sorted by content
2.2 DVD discs sorted by content
I also added IComparable<Product>
to more easily make it comparable with other products.
abstract class Product : IComparable<Product>
{
public string Name { get; set; }
public decimal Price { get; set; }
public string Barcode { get; set; }
protected abstract int InternalSortOrder { get; }
protected virtual string SortBy { get {return Name;} }
public int CompareTo(Product obj)
{
var sameType = string.Compare(GetType().Name, obj.GetType().Name, StringComparison.Ordinal) == 0;
var sameBaseType = GetType().BaseType != null && obj.GetType().BaseType != null &&
string.Compare(GetType().BaseType.ToString(), obj.GetType().BaseType.ToString(),
StringComparison.Ordinal) == 0;
// They have the same base type, but not the same type. Order by base type first.
if (!sameType && !sameBaseType && GetType().BaseType != null && obj.GetType().BaseType != null)
{
// Order by base type first.
return string.Compare(GetType().BaseType.ToString(), obj.GetType().BaseType.ToString(),
StringComparison.Ordinal);
}
// it's the same base type (eg. book or disc)
if (sameBaseType)
{
// Order by sort order.
if (obj.InternalSortOrder != this.InternalSortOrder)
{
return InternalSortOrder.CompareTo(obj.InternalSortOrder);
}
}
if (sameType)
{
// Same sort order. We sort by name.
return string.Compare(SortBy, obj.SortBy, StringComparison.Ordinal);
}
// Order by Type.
return string.Compare(GetType().Name, obj.GetType().Name, StringComparison.Ordinal);
}
}
abstract class Book : Product
{
public int PagesCount { get; set; }
}
class ProgrammingBook : Book
{
public string ProgrammingLanguage { get; set; }
protected override int InternalSortOrder
{
get { return 1; }
}
}
class CulinaryBook : Book
{
public string MainIngridient { get; set; }
protected override int InternalSortOrder
{
get { return 2; }
}
}
class EsotericBook : Book
{
public int MininumAge { get; set; }
protected override int InternalSortOrder
{
get { return 3; }
}
}
abstract class Disc : Product
{
internal enum Content
{
Music,
Video,
Software
}
protected override string SortBy
{
get { return DiscContent.ToString(); }
}
public Content DiscContent { get; set; }
}
class CdDisc : Disc
{
protected override int InternalSortOrder
{
get { return 1; }
}
}
class DvdDisc : Disc
{
protected override int InternalSortOrder
{
get { return 2; }
}
}
UPDATE:
I've added virtual
SortBy
in Product
. It will go to Name
by default, but Disc
will return Content
.