How do I get consistent behavior with matchadd color column?

Question

After watching Damian Conway's talk, I added the following two lines to my .vimrc.

highlight ColorColumn ctermbg=magenta
call matchadd('ColorColumn', '\%81v', 100)

My objective is to get the 81st column to be highlighted whenever a line goes beyond 80 characters. Unfortunately, if I open a new file and type 80i-, then I get highlighting on the 81st column even though there is no character there.

If I manually delete the 80th character and type it again, I sometimes get highlighting on the 81st column and sometimes don't. When I have 80 characters, I'd prefer not to have the 81st column highlighted.

How can I achieve this behavior?

Answer 1

The solution I'm using nowadays is:

matchadd('ColorColumn', '\%81v\s*\zs\S', 100)

That version highlights the first non-space character after column 80, which I find more useful.

Answer 2

After digging around a bit on the internet, I found this page which achieves a similar effect but is more specific in the match.

The fix is to add a . after the v.

call matchadd('ColorColumn', '\%81v.', 100)