Question

I am curious on how the following code works, especially the part the contains the delegate stuff since I am new to it. Also, are there any bottlenecks in the code, for example, would using a SortedDictionary be better than using a List and then sorting it using LINQ? Ok, here is the code:

public class ColorManager {     private List<ColorData> colorCodes = new List<ColorData>();      public List<ColorData> ColorCodes     {         get         {             var sortList = from a in this.colorCodes                            orderby a.colorCode ascending                            select a;              return sortList.ToList();         }     }      public void FillData(DataTable table)     {         for(int row = 0; row < table.Rows.Count; row++)         {             ColorData cData = new ColorData();             string name = table.Rows[row]['Color'].ToString().Trim();              if(!this.colorCodes.Exists(                 delegate(ColorData e)                 {                     return e.ColorCode == name;                 }))             {                 cData.Add(table.Rows[row]['Color'].ToString());                 this.colorCodes.Add(cData);             }             else             {                 this.colorCodes.Find(                     delegate(ColorData e)                     {                         return e.ColorCode == name;                     }).Count++;             }         }      } } 

Answer 1

I am curious on how the following code works, especially the part the contains the delegate stuff since I am new to it.

First take a look at this ColorCodes property accessor:

        var sortList = from a in this.colorCodes                        orderby a.colorCode ascending                        select a; 

It returns a list of all the color codes (this.colorCodes) in ascending order (...orderby a.colorCode ascending). Simple so far. How about the meatier FillData method?

First, we’ll loop over every row in this table:

    for(int row = 0; row < table.Rows.Count; row++)     { 

Then, we’re going to look at the Color column of the current row.

        ColorData cData = new ColorData();         string name = table.Rows[row]['Color'].ToString().Trim(); 

If that column has no match in our list of color codes, this if condition is true. The Exists method takes a single-argument function that returns a bool, which is what this anonymous delegate is: a single-argument (ColorData e) function that returns a boolean (e.ColorCode == name). It gets negated (!this.[...]), so if a match is found, the condition is false.

        if(!this.colorCodes.Exists(             delegate(ColorData e)             {                 return e.ColorCode == name;             }))         {             cData.Add(table.Rows[row]['Color'].ToString());             this.colorCodes.Add(cData);         } 

Otherwise, if there’s a match, find the name using another anonymous delegate, and add one to the count of items of that color.

        else         {             this.colorCodes.Find(                 delegate(ColorData e)                 {                     return e.ColorCode == name;                 }).Count++;         }     }  

Note that this code is somewhat inefficient, since the two different anonymous delegates really do the same thing and could be shared.