C# in Depth

136 CHAPTER 4 Saying nothing with nullable typesdesired short-circuiting functionality for Booleans. A method returning a bool? can beused to obtain an initial definitely equal, definitely not equal or unknown result based on thereferences, however. The complete code of PartialComparer on this book’s websitecontains the appropriate utility method and examples of its use.4.5 SummaryWhen faced with a problem, developers tend to take the easiest short-term solution,even if it’s not particularly elegant. That’s often exactly the right decision—we don’twant to be guilty of overengineering, after all. However, it’s always nice when a goodsolution is also the easiest solution.Nullable types solve a very specific problem that only had somewhat ugly solutionsbefore C# 2. The features provided are just a better-supported version of a solutionthat was feasible but time-consuming in C# 1. The combination of generics (to avoidcode duplication), CLR support (to provide suitable boxing and unboxing behavior),and language support (to provide concise syntax along with convenient conversionsand operators) makes the solution far more compelling than it was previously.It so happens that in providing nullable types, the C# and Framework designershave made some other patterns available that just weren’t worth the effort before.We’ve looked at some of them in this chapter, and I wouldn’t be at all surprised to seemore of them appearing over time.So far our two new features (generics and nullable types) have addressed areaswhere in C# 1 we occasionally had to hold our noses due to unpleasant code smells.This pattern continues in the next chapter, where we discuss the enhancements to delegates.These form an important part of the subtle change of direction of both the C#language and the .NET Framework, toward a slightly more functional viewpoint. Thisemphasis is made even clearer in C# 3, so while we’re not looking at those features quiteyet, the delegate enhancements in C# 2 act as a bridge between the familiarity of C# 1and the potentially revolutionary style of C# 3.Licensed to Rhona Hadida