VB Ordering of Anonymous Type Properties change with VS 2008 SP1 by ThinqLinq

The VS 2008 SP1 includes lots of new features (more than a typical service pack, but that's another matter). There are a number of smaller enhancements that could easily go un-noticed otherwise. One of these is to fix a bug in the way the VB compiler generates anonymous types.

In most cases, you will only notice this if you are binding an anonymous projection to a DataGridView or the ASP GridView. With these controls, you will find that the columns used to be generated alphabetically rather than in the order in which they were declared in the anonymous type projection. Consider the following query (using the Northwind Customers table of course):

With VS 2008 RTM, a grid bound to these results would display the columns in the following order unless you explicitly set the columns: Address, CompanyName, ContactName, ContactTitle. Notice here that they are listed alphabetically. Interestingly if you use the same query in C#, the columns would be displayed retaining the order of the projection.

To determine the cause for the difference, one must view the actual IL using ILDASM. Comparing the C# with VB IL, you can see that the C# compiler retains the order where-as VB alphabetized it. No, you can't use Lutz's Reflector this time because he too alphabetizes the properties from the IL.

This was true until VS 2008 SP1 which fixed this bug. Now, the anonymous types are generated in the order in which they were declared and the column ordering is retained. Running the same query we had above results in the following column ordering with VB 2008 SP1: CompanyName, ContactTitle, ContactName, Address.

Thanks to the VB team for fixing this bug in the compiler.