C# in Depth

356 CHAPTER 13 Elegant code in the new eraThis works well when a single, isolated aspect of the component needs to be specialized.It’s certainly not a complete replacement of inheritance, nor would I want itto be (the title of this section notwithstanding)—but it allows a more direct approachto be used in many situations. Using interfaces with a small set of methods has oftenbeen another way of providing custom behavior, and delegates can be regarded as anextreme case of this approach.Of course, this is similar to the point made earlier about a more functional bias, butit’s applied to the specific area of inheritance and interface implementation. It’s notentirely new to C# 3, either: List made a start in .NET 2.0 even when only C# 2 wasavailable, with methods such as Sort and FindAll. Sort allows both an interface-basedcomparison (with IComparer) and a delegate-based comparison (with Comparison),whereas FindAll is purely delegate based. Anonymous methods made these calls relativelysimple and lambda expressions add even more readability.In short, when a type or method needs a single aspect of specialized behavior, it’sworth at least considering the ability to specify that behavior in terms of a delegateinstead of via inheritance or an interface.All of this contributes to our next big goal: readable code.13.3 Readability of results over implementationThe word readability is bandied around quite casually as if it can only mean one thingand can somehow be measured objectively. In real life, different developers find differentthings readable, and in different ways. There are two kinds of readability I’dlike to separate—while acknowledging that many more categorizations are possible.First, there is the ease with which a reader can understand exactly what your codeis doing at every step. For instance, making every conversion explicit even if there’s animplicit one available makes it clear that a conversion is indeed taking place. This sortof detail can be useful if you’re maintaining code and have already isolated the problemto a few lines of code. However, it tends to be longwinded, making it harder tobrowse large sections of source. I think of this as “readability of implementation.”When it comes to getting the broad sweep of code, what is required is “readabilityof results”—I want to know what the code does, but I don’t care how it does it rightnow. Much of this has traditionally been down to refactoring, careful naming, andother best practices. For example, a method that needs to perform several steps canoften be refactored into a method that simply calls other (reasonably short) methodsto do the actual work. Declarative languages tend to emphasize readability of results.C# 3 and LINQ combine to improve readability of results quite significantly—at thecost of readability of implementation. Almost all the cleverness shown by the C# 3compiler adds to this: extension methods make the intention of the code clearer, butat the cost of the visibility of the extra static class involved, for example.This isn’t just a language issue, though; it’s also part of the framework support.Consider how you might have implemented our earlier user query in .NET 1.1. Theessential ingredients are filtering, sorting, and projecting:Licensed to Rhona Hadida