C# in Depth

274 CHAPTER 10 Extension methodsFew of these guidelines are particularly clear-cut—to some extent you’ll have to feelyour own way to the best use or avoidance of extension methods. It’s perfectly reasonableto never write your own extension methods at all but still use the LINQ-relatedones for the readability gains available there. It’s worth at least thinking about what’spossible, though.10.5 SummaryThe mechanical aspect of extension methods is straightforward—it’s a simple featureto describe and demonstrate. The benefits (and costs) of them are harder to talkabout in a definitive manner—it’s a touchy-feely topic, and different people arebound to have different views on the value provided.In this chapter I’ve tried to show a bit of everything—early on we looked at whatthe feature achieves in the language, before we saw some of the capabilities availablethrough the framework. In some ways, this was a relatively gentle introduction toLINQ: we’ll be revisiting some of the extension methods we’ve seen so far when wedelve into query expressions in the next chapter, as well as seeing some new ones.A wide variety of methods are available within the Enumerable class, and we’ve onlyscratched the surface. An exhaustive description with examples of all the methodswould take most of a book on its own, and it’d become rather dull. It’s much moreinteresting to come up with a scenario of your own devising (whether hypothetical orin a real project) and browse through MSDN to see what’s available to help you. I urgeyou to use a sandbox project of some description to play with the extension methodsprovided—it does feel like play rather than work, and you’re unlikely to want to constrainyourself to just looking at what you need to achieve your most immediate goal.The appendix has a list of the standard query operators from LINQ, which coversmany of the methods within Enumerable.New patterns and practices keep emerging in software engineering, and ideasfrom some systems often cross-pollinate to others. That’s one of the things that keepsdevelopment exciting. Extension methods allow code to be written in a way which waspreviously unavailable in C#, creating fluent interfaces and changing the environmentto suit our code rather than the other way around. Those are just the techniques we’velooked at in this chapter—there are bound to be interesting future developmentsusing the new C# features, whether individually or combined.The revolution obviously doesn’t end here, however. For a few calls, extensionmethods are fine. In our next chapter we look at the real power tools: query expressionsand full-blown LINQ.Licensed to Rhona Hadida