I got an email from a reader in Spain that read, in part

I did a test and got an AttributeError. Maybe you are interested in debugging it.

The email referred to

which I wrote in January of last year. I pulled down the code, gave it a whirl, and found that I had a bug in it.

Wrong code ⇒ bad code.

I wanted to debug it.

For a long time, Model-View-Controller, Model-View-Presenter, and (with far slimmer adoption) associated patterns represented the accepted patterns for the objects that participated in organizing the responsibilities found in a graphical user interface. But, back in November 2010, the Microsoft® patterns and practices team published the Model-View-ViewModel (MVVM) Pattern that takes advantage of their WPF and Silverlight user interface toolkits. Now, we have MVVM toolkits in lots of different languages and rendering targets. This post discusses the pattern, its requirements, and its awesomeness.

I had planned on putting up another post when Monday rolled around, one that continued the MVWTF discussion I started last week. My friend, Ed, reported that the post seemed incomplete because I dropped the MVVM ball. I couldn’t help but agree.

On Sunday, I started the MVVM post. However, it has run away from me. Far, far and away. I have put about 12 hours of work into the post and I’ve only half completed it. This has not resulted from an immense amount of content; rather, it has resulted from trying to create precise content. To quote Dr. Andre de Korvin, “We must lose precision to make significant statements about complicated systems.” Well, I ain’t losing no precision, here, so my significant statements take longer.