Practical .NET

Shortcuts for Defining Anonymous Objects in C# and VB

Here are two ways to save some typing when defining anonymous objects. One only works in Visual Basic, though.

If you've created an anonymous object, you've probably written code like this:

Dim anon = New With {
                     .FirstName = "Peter",
                     .LastName = "Vogel"
                     }

This code would give you a new, anonymous object with two properties (FirstName and LastName), set to "Peter" and "Vogel," respectively, and both of type string.

However, you can save yourself some typing if you're setting your anonymous object's properties from named values. If the values you're using have names, then the compiler will use those names for the properties on your anonymous object.

This code (one in C# and one in Visual Basic) will generate the same result as my previous example. One does it by getting values from variables named FirstName and LastName and the other does it by getting values from properties on another object:

string FirstName = "Peter";
string LastName = "Vogel";
var anon = new { FirstName, LastName };

Dim ct As New Customer("A123")
Dim anon = New With {ct.FirstName, ct.LastName}

While these shortcuts work in both C# and Visual Basic, if you're working Visual Basic and LINQ you have another shortcut. In Visual Basic, if the Select clause in your LINQ statement returns multiple values, then LINQ will automatically define an anonymous object for you. This code, for example

Dim custName = from c in db.Customers
               Select(c.FirstName, c.LastName)

will generate a collection of anonymous objects with properties called FirstName and LastName.

About the Author

Peter Vogel is a system architect and principal in PH&V Information Services. PH&V provides full-stack consulting from UX design through object modeling to database design. Peter tweets about his VSM columns with the hashtag #vogelarticles. His blog posts on user experience design can be found at http://blog.learningtree.com/tag/ui/.

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