Working on a file that already have kerning defined, I wanted to rearrange the kerning groups:
Instead of one @a class with exceptions for colliding accents, I want to have one @a class and one @a-accents class. I am also doing the same to other classes – i.e. @o will be split in @o and @o-accents. Is there a way to copy the kerning pairs from @ n to @ n-accents?
Hmm. I found Toshi’s Copy Kerning Pairs script. It gets me halfway there, but won’t suffice when I have multiple split classes. If I copy the @a pairs to @a-accent, and the @h pairs to @h-accent, I still won’t have any kerning between @a-accent and @h-accent.
That would be more than copying, that is actually creating new kerning.
Yes, it multiplies, now I remember that was one of the reasons I abandoned the idea again. That, and that it is hard to keep up to date. E.g., if you change something in a-h, then it is not clear if the change should also trickle down to a-hAccents, aAccents-h, and/or also aAccents-hAccents.
Have you tried using MetricsMachine for copying kerns? That’s how I do it. Export a UFO, makes changes in MetricsMachine, import the new metrics data back to the .glyphs file.