It should be clear from the additional content what’s new: I added coverage of the significant C#4.0 features like dynamic invocation and named / optional parameters. New library additions like PLINQ are also covered.
It’s much harder to see how I decided which items to drop. There are 15 completely new items in the 2nd edition, so that meant finding 15 items to drop. (Several other items have the same title, but were significantly rewritten – that will be the subject of another blog post.) Here’s how I decided which items to remove:
Items that are less important now. A number of the items in the first edition discussed techniques that were much more important before generics were available. Some of these items were those that discussed boxing and unboxing, the collection classes, and the data set class. All of those techniques and libraries were far more useful in C# 1.x than in the current .NET universe.
Items that have become common practice. C# has been around for almost a decade, and the community is much more mature than it was in 2004, when Effective C# was published. Some of the items are part of the conventional wisdom now
Items that assumed your last language was C++ or Java. The early adopters of C# were developers that came from C++ (on the Windows platform) along with some developers that came from Java. That’s no longer true. College grads (since 2002 or so) are using C# for their first professional programming experience. Others are coming from VB, Ruby, Python, or PHP. (I’m not claiming that C# is grabbing market share from all those languages; the migration happens in all directions.) It just wasn’t right to assume that every C# developer has C++ or Java experience anymore.
The poster child for dropping items is the original Item 41, where I advocated using DataSets rather than implementing IBindingList yourself. I didn’t rewrite this item because the obvious answer now is to use BindingList<T> when you need the IBindingList capability. If you were using DataSets for some other reason, pick some other generic collection type. There are many, and the options grew again in .NET 4.0. Those generic collections have better APIs (the type parameter means the compiler ensures type correctness), and better performance (boxing / unboxing doesn’t apply. It’s not often that it’s trivial to get better performance and better chances at correctness. Even in the 1.x days, I didn’t advocate using DataSets are part of a service API. That was and still is a painful choice.
There’s also been many enhancements in the .NET framework that mean there are better data solutions. LINQ, along with the query syntax pattern (See Item 36 in More Effective C#), means there are much better ways to work with data in .NET 4.0. Chapters 4 and 5 of More Effective C# discuss these important techniques. The entity framework has matured, and is a better way to handle data transfer between layers and machine boundaries. (I still need to look more closely at the latest EF, I know some of the changes, but not all).