From 0a9ff4b61293a3e94c88882f94c7683616a49f90 Mon Sep 17 00:00:00 2001
From: Mikhail Glushenkov
OptionPreprocessor is basically a single big case expression, which is evaluated only once right after the plugin is loaded. The only allowed actions -in OptionPreprocessor are error, warning and two special actions: +in OptionPreprocessor are error, warning, and two special actions: unset_option and set_option. As their names suggest, they can be used to -set or unset a given option. To set a parameter option with set_option, use -the two-argument form: (set_option "parameter", "value"). For convenience, -set_option and unset_option also work on lists (that is, instead of -[(unset_option "A"), (unset_option "B")] you can use (unset_option ["A", -"B"])).
+set or unset a given option. To set an option with set_option, use the +two-argument form: (set_option "parameter", VALUE). Here, VALUE can be +either a string, a string list, or a boolean constant. +For convenience, set_option and unset_option also work on lists. That +is, instead of [(unset_option "A"), (unset_option "B")] you can use +(unset_option ["A", "B"]). Obviously, (set_option ["A", "B"]) is valid +only if both A and B are switches.