Eli, Thanks for taking the time to respond. The separator character I use is simply the 'pipe' character, "|". The purpose for me is to clearly delineate the text/code from the line numbers in a way that makes it easier to grok the text being displayed. My brain sees the numbers as part of the code with the current formatting of display-line-numbers, but maybe I'm uniquely incapable. I completely understand feature creep, and the reason I've switched to display-line-numbers *because* of performance. Using a combination of outline-minor-mode (with folding) and linum-mode made emacs run at 100% cpu while moving the cursor in the terminal. Not to mention other linum bugs. Best. On Fri, Sep 10, 2021 at 6:31 AM Eli Zaretskii wrote: > > Date: Fri, 10 Sep 2021 01:40:45 -0600 > > From: "Michael Gallagher (CIRES/NOAA)" via "Bug reports for GNU Emacs, > > the Swiss army knife of text editors" > > > > linum mode has several performance issues but has the convenient ability > > to format the line numbers in a way chosen by the user. It would be > > wonderful to be able to add a "separator" character of choosing to > > display-line-numbers-mode. > > Please tell more about this "separator character": what should it be > and how will it be displayed? And what is its purpose in the first > place? > > I'd like to avoid adding a general format-style extension to the > native line numbers, that's a kind of creeping featurism that will > eventually slow down redisplay too much, something that the > display-line-numbers implementation explicitly attempts to avoid. > People who must have the full-fledged format capability could simply > use linum-mode instead. > > > I would be happy to try to contribute code but I'm unsure of where > > to start with such a task. > > The code is in xdisp.c, if that's what you meant to ask. > > Thanks. > -- Michael Gallagher, PhD CIRES Research Scientist Polar Observations and Processes Team (ESRL/NOAA/PSD) 325 Broadway, Boulder, Colorado 80305