Book Image

C# Programming Cookbook

By : Dirk Strauss
Book Image

C# Programming Cookbook

By: Dirk Strauss

Overview of this book

During your application development workflow, there is always a moment when you need to get out of a tight spot. Through a recipe-based approach, this book will help you overcome common programming problems and get your applications ready to face the modern world. We start with C# 6, giving you hands-on experience with the new language features. Next, we work through the tasks that you perform on a daily basis such as working with strings, generics, and lots more. Gradually, we move on to more advanced topics such as the concept of object-oriented programming, asynchronous programming, reactive extensions, and code contracts. You will learn responsive high performance programming in C# and how to create applications with Azure. Next, we will review the choices available when choosing a source control solution. At the end of the book, we will show you how to create secure and robust code, and will help you ramp up your skills when using the new version of C# 6 and Visual Studio
Table of Contents (21 chapters)
C# Programming Cookbook
Credits
About the Author
Acknowledgements
About the Reviewer
www.PacktPub.com
Preface
Index

Creating code contract invariant


Something that is defined as invariant tells us that it will never change. It will always be the same, no matter what. This brings up a vast array of use cases if we consider this in the context of code contracts. The invariant code contract is basically used to validate the internal state of a class. So, what do we mean by the "internal state?" Well, the properties of the class give that class a specific state. Let's assume that we wanted to guarantee that the properties of the class we are using only accept specific values, thereby assuring the internal state of that class. This is where the code contract invariant comes into play.

Getting ready

You can understand the use of the invariant better with the use of the following example. Assume that the class needs to store dates. We can't ever store a date in the past though. Any date used in the class must be a current or future date.

How to do it…

  1. Before you go on, ensure that you have added the code contracts...