C# 6.0 in a Nutshell, 6th Edition

Chapter 13. Diagnostics and Code Contracts

When things go wrong, it’s important that information is available to aid in diagnosing the problem. An IDE or debugger can assist greatly to this effect—but it is usually available only during development. Once an application ships, the application itself must gather and record diagnostic information. To meet this requirement, the .NET Framework provides a set of facilities to log diagnostic information, monitor application behavior, detect runtime errors, and integrate with debugging tools if available.

The .NET Framework also allows you to enforce code contracts. Introduced in Framework 4.0, code contracts allow methods to interact through a set of mutual obligations and fail early if those obligations are violated.

The types in this chapter are defined primarily in the System.Diagnostics and System.Diagnostics.Contracts namespaces.

Conditional Compilation

You can conditionally compile any section of code in C# with preprocessor directives. Preprocessor directives are special instructions to the compiler that begin with the # symbol (and, unlike other C# constructs, must appear on a line of their own). Logically, they execute before the main compilation takes place (although in practice, the compiler processes them during the lexical parsing phase). The preprocessor directives for conditional compilation are #if, #else, #endif, and #elif.

The #if directive instructs the compiler to ignore a section of code unless a specified ...