`bin/tapioca dsl --only` should not purge existing directory

[KaanOzkan]

I believe --only is mostly used as a debugging tool to test specific compiler output. However, its output is hard to understand since tapioca purges the files that aren't generated and creates a large diff https://github.com/Shopify/tapioca/blob/5a9d90c9b6f65681609cd38a84595bd3639646b7/lib/tapioca/commands/abstract_dsl.rb#L88

We could skip the purging if --only is present. Am I missing any valid use cases where --only will be used permanently by a repo? In that case we could have a separate flag to skip purging.

[drewhoffer]

Hi, I'd like to work on this if it's available.

[KaanOzkan]

Hi, I'd like to work on this if it's available.

Thank you. It's available. We should also output a log saying something like "Skipping purging because of --only flag" to inform the user.