Background

• related to All command line arguments that alter output should be configurable in config file #47

While it was only recently that I introduces Sourcery templates for generating decoder logic for the ConfigOptions file, it actually lead me to take some inspiration from Swift Argument Parser and to write my own mini library called ConfigurationParser.

Similar to ArgumentParser, it lets you define ParsableConfiguration types and brings all kinds of useful improvements compared to just decoding data using YAMLDecoder that we had been taking advantage of.

The result is that a lot of the custom decoding code written in the CreateOptions target is now no longer required. In this change I delete it all and I update ConfigOptions to become a ParsableConfiguration type which involves the following:

1. Conform to the ParsableConfiguration protocol (no requirements other than init()
2. Annotate every property as an @Option
   • This allows the parser to discover the property and its default value.
   • It also allows us to read all option metadata via ConfigOptions.options which is powerful (read on).

Since I deleted the custom decoding code, I did also have to make up for it since that's how #111 worked. To combat this, I introduced a small @OptionSetDecodable property wrapper that handles things.

While in this change we are just using the library to replicate what we previously did manually, there are two other powerful features that I hope to take advantage of:

Overrides

ConfigurationParser allows you to pass overrides when parsing, we can pull these from the CLI arguments which helps with #47 because in theory you can override anything via the command line arguments.

Documentation

The @Option annotation lets you include documentation and we can leverage this with a plugin that can replace Sourcery in terms of generating documentation.