Beginning C# 7 Programming with Visual Studio 2017

12Generics

WHAT YOU WILL LEARN IN THIS CHAPTER:

• Discovering generics
• Using generic classes provided by the .NET Framework
• Defining your own generics
• Learning how variance works with generics

WROX.COM CODE DOWNLOADS FOR THIS CHAPTER

The wrox.com code downloads for this chapter are found on this book's webpage on Wrox.com on the Download Code tab. The code can also be found at http://github.com/benperk/BeginningCSharp7. The code is in the Chapter12 folder and individually named according to the names throughout the chapter.

This chapter begins by looking at what generics are. You learn about generics in fairly abstract terms at first, because learning the concepts behind generics is crucial to being able to use them effectively.

Next, you see some of the generic types in the .NET Framework in action. This will help you understand their functionality and power, as well as the new syntax required in your code. You'll then move on to define your own generic types, including generic classes, interfaces, methods, and delegates. You also learn additional techniques for further customizing generic types: the default keyword and type constraints.

Finally, you'll look at covariance and contravariance, two forms of variance that were introduced in C# 4 and that allow greater flexibility when using generic classes.

WHAT ARE GENERICS?

To best illustrate what generics are, and why they are so useful, recall the collection classes from the previous chapter. You saw how basic collections can be contained ...