Inject C# code before build

Question

How to inject a new code in existing C# code (not MSIL) before compiling, but not change .cs file?

Answer 1

You can use the Text Template Transformation Toolkit (T4) to handle this type of scenario.

Answer 2

Use T4 templates which write to partial class files. This is the pattern used by Visual Studio--auto-generated code goes in partial files, while your code goes in the main .cs file.