How do I get the path to the current C# source code file?

Question

How do I get the path to the current C# source code file, or the directory the file is stored in? (I'm answering this question myself because I didn't find anything on it with a Google search.)

(Note: This is not asking for Assembly.GetEntryAssembly().Location, which gives the path to the executable, nor Directory.GetCurrentDirectory(), which gives the directory the process was invoked from.)

Answer 1

Do this:

using System.Runtime.CompilerServices;

private static string GetThisFilePath([CallerFilePath] string path = null)
{
    return path;
}

var path = GetThisFilePath(); // path = @"path\to\your\source\code\file.cs"
var directory = Path.GetDirectoryName(path); // directory = @"path\to\your\source\code"

How it works: Roslyn specially recognizes the CallerFilePath, CallerLineNumber, and CallerMemberName attributes (the last one might look familiar to you if you've done some MVVM programming). At compile-time, it populates parameters marked with these attributes with the actual file path / line number / member name of the caller. If you compile and decompile the above code, the assignment to path will look like

var path = GetThisFilePath(@"path\to\your\source\code\file.cs");