Many posts have been written about the fact that you cannot specify a config file for class libraries. While I understand the logic of putting the config file in the host process instead, there are always valid reasons for wanting to go outside the use case scenarios envisioned by the designer. My example would by COM Interop. If you have a .NET class library that requires some amount of configurability, and you use COM Interop, you cannot use the host process' config file because it doesn't exist. Instead, you need to get the configurability another way. I thought of the registry, a simple INI file, and a config file, and in the end, I settled on the config file. By doing this, I was getting people here and in the field used to the config file concept. However, that meant that I needed to provide custom support for maintaining this config file.

There are several options, like the EntLib FileConfigurationSource, creating a custom Reader to read arbitrary config files, etc. I came across Mike Woodring's AppSettings implementation, which gives a pretty close approximation of how config file logic works. It doesn't use the new .NET 2.0 sections, but it's a good start and got my code working with minimal trouble.