Concise Code to Enable/Disable WinForm Controls

Let's say you have a check box (cb1)  on a form that enables a text box (txt1)  and disables a listbox (lst1).  You can write a statement that shows this dependency on 2 lines:

  txt1.Enabled = cb1.Checked;

  lst1.Enabled = !cb1.Checked;

This works fine. However, we repeat the reference to the check box state twice.
There is a way to write the above statements on the same line:

   lst1.Enabled = !(txt1.Enabled = cb1.Checked);

Looks simple when you get it right. But it took me a few minutes to figure it out.

Examine Columns in ASP.NET Dynamic Data MetaTable

This is how you get access to all columns in a MetaTable that serves as a data source to your controls like a DetailsView or a GridView. Dynamic Data generates the following code for each ASP.NET page by default:

   protected MetaTable table;

   protected void Page_Load(object sender, EventArgs e)

   {

       table = DetailsDataSource.GetTable();

       Title = table.DisplayName;

   }

The MetaTable class has a Columns property that returns a collection of MetaColumns for the table. This allows us to enumerate through the collection and check for any custom attributes on table columns:

    

   foreach (MetaColumn column in table.Columns)

   {

      if (column.Attributes.OfType<MyCustomAttribute>().Count() > 0)

          ......

      }

   }

This is based on a tip found at this blog.

Reverse .NET SortedList

 This post shows how you could reverse a SortedList in C# by its keys:

SortedList<string, string> strlist = new SortedList<string, string>();

strlist.Add("f3", "xxx");

strlist.Add("f1", "ccc");

strlist.Add("f2", "aaa");

foreach (KeyValuePair<string, string> kvp in strlist)

{

    Console.WriteLine("Key = {0}, Value = {1}", kvp.Key, kvp.Value);

}           

Console.WriteLine("reverse the list");

IEnumerable<KeyValuePair<string, string>> revList = strlist.Reverse();

foreach (KeyValuePair<string, string> kvp in revList)

{

    Console.WriteLine("Key = {0}, Value = {1}", kvp.Key, kvp.Value);

}