Professional C# and .NET, 2021st Edition

12Reflection, Metadata, and Source Generators

WHAT'S IN THIS CHAPTER?

• Using custom attributes
• Inspecting the metadata at runtime using reflection
• Working with the dynamic type
• Creating dynamic objects with ExpandoObject
• Compiling code with source generators

CODE DOWNLOADS FOR THIS CHAPTER

The source code for this chapter is available on the book page at www.wiley.com. Click the Downloads link. The code can also be found at https://github.com/ProfessionalCSharp/ProfessionalCSharp2021 in the directory 1_CS/ReflectionAndSourceGenerators.

The code for this chapter is divided into the following major examples:

• LookupWhatsNew
• TypeView
• VectorClass
• WhatsNewAttributes
• Dynamic
• DynamicFileReader
• CodeGenerationSample

All the sample projects have nullable reference types enabled.

INSPECTING CODE AT RUNTIME AND DYNAMIC PROGRAMMING

This chapter focuses on custom attributes, reflection, dynamic programming, and source code generation during the build process with C# 9 source generators. Custom attributes are mechanisms that enable you to associate custom metadata with program elements. This metadata is created at compile time and embedded in an assembly. Reflection is a generic term that describes the capability to inspect and manipulate program elements at runtime. For example, reflection allows you to do the following:

• Enumerate the members of a type
• Instantiate a new object
• Execute the members of an object
• Find out information about a type
• Find out information about ...