Switch to dictionary format for parameterized rules

[scottrhoyt]

In addition to not being self documenting, the current array format of parameterizing config values in .swiftlint.yml is proving to be a hurdle to allowing more customization for rules (see #191 #130 #231 ). It's also complicating providing a better way to merge nested configs for #301 .

I propose we switch the format to a dictionary format. e.g.:

variable_name_max_length:
  warning: 40
  error: 60
  exclude: "id"

This would require an overhaul to how ParameterizedRule works. It would also make breaking changes for previous versions of the .swiftlint.yml file, so it probably shouldn't happen until at least the 1.0 release. However, I'd be willing to start looking at how to best accomplish this.

[jpsim]

This does seem like the right direction, at the expense of making the simple case more verbose (variable_name_max_length: 20).

I think this could be done at any time, either pre- or post-1.0. I haven't really defined what SwiftLint 1.0 would look like. I should probably start a discussion about that.

[scottrhoyt]

I think I've worked out a nice way to accomplish this. I can also preserve the simple case (variable_name_max_length: 20). Working on a POC right now. Let me work the problem a bit more, but I'm pretty sure I've got it nailed, and it should provide some nice additional benefits. I'll report back here once I've fleshed it out a bit more.

[jpsim]

Awesome! It's great to see you working on this 😄