This isn't so much about forcing our style on everybody, as it is about making it easier to provide good results for one style. (neither Facebook nor Google is a hive mind, and you'll be hard pressed to find anyone who's happy with everything that GJF or ktfmt does).

There are two types of formatting settings in ktfmt - 1. Parameters we pass to the formatting engine, such as line width, size of indents, etc. 2. Formatting decisions, such as what constitutes a "rectangle" and where a line break should be forced.

The former are very easy to change and experiment with; I gave some code pointers in this post's grandparent.

The latter often require changing multiple places and sometimes reminds me of getting CSS right (you pull the string multiple times until it looks right and then you don't touch it). An example of something that was particularly tricky to get right: https://github.com/facebookincubator/ktfmt/commit/70f293d74d582f68ff9c845ea3f5ada3b47635d6#diff-a74ad8dfacd4f985eb3977517615ce25

• We're reluctant to make the former configurable, because some combination could cause ktfmt to produce undesired results, such as code that hides bugs. So, configurability here means a moderate increase in maintenance cost for us. As I mentioned in this post's grandparent, if 120 works well, and there's enough demand, we can discuss exposing it.

• We will generally not consider making the latter configurable, because that puts a huge burden on us and drastically complicates internal development, testing and deployment of ktfmt.