(Very) late to this very interesting exchange. I can only have a proper sit down at weekends, so I couldn't make it in time, but here is was my submission for a new tool operating as RegexpReplace "^.*".
This is transcribed from my phone, where I usually jot down ideias when I'm not at home.
Feed S n
Wording:
- derived from "Line Feed" (LF); also from the verb form "to feed".
Usage:
- used as Feed or Feed "": Clears current buffer content; mimics a new/fresh/clean line (similar to RegexpReplace "^.*" "");
- used as Feed "S": Clears current buffer content AND inserts contents of S, either string or %output% (similar to RegexpReplace "^.*" "string|%output%"); moves pointer to 1;
used as Feed "S" 1: inserts contents of S (string|%output%) at current pointer position (as in 'feeding' S); moves pointer to 1st character after appended content (previously suggested as Splice).
Inconveniences:
Using Feed "" 1 would, in effect, do nothing.
(behavior already happens in Replace S S; so no big deal)
I'm leaving this here, as it may inspire others.
EDIT: I just read about Use; and here's an idea:
Use S 1: Use contents of S as current input. If the second parameter is set to 1, S is inserted(/spliced? /added? / appended?) at current pointer position.