Today I learned how to fold/unfold in Vim; it's quite handy.
Unexpectedly, when I exit a file and reenter it, the folds I created are gone (unfolded).
In our company's large project there are quite a lot of sticky (legacy) code blocks which are kind of obsolete but indispensable.
I really need to fold them nearly permanently.
Is there a brief way to tell Vim to save my folding preferences for a file?
I do exactly this for one file I refer to a lot NOTES.otl I performed the following in my .vimrc:
" Useful for my Quick Notes feature in my tmuxrc
augroup QuickNotes
au BufWrite,VimLeave NOTES.otl mkview
au BufRead NOTES.otl silent loadview
augroup END
What this means is that in your case you can handle manual folds using the :mkview and :loadview commands.
An easy to fold the legacy codes permanently is to use the foldmethod of "marker".
You can enclose the codes with the markers "{{{" and "}}}", and add a modeline to the file, like:
/* vim: set foldmethod=marker : */
'foldmethod'=marker is an alternative approach to 'foldmethod'=manual. Note that the markers {{{, }}} will be included with the file.
A more general approach (not just for QuickNotes but for all files) would be as follows:
" Save and restore manual folds when we exit a file
augroup SaveManualFolds
autocmd!
au BufWinLeave, BufLeave ?* silent! mkview
au BufWinEnter ?* silent! loadview
augroup END
For more information, see the view-sessions, section with includes the mkview and loadview commands.
:mkviewand:loadviewcommands could help. You could try adding these 2 lines inside your vimrcau BufWinLeave *.c mkviewandau BufWinEnter *.c silent loadviewand adapt them to your specific needs. These are autocommands that will be automatically executed whenever you leave a buffer for the first one, and when you enter a buffer for the second one, but only for C files. I've copied them from the help of the:mkviewcommand (:help :mkview).'viewoptions'containsfolds. If you want the autocommands to be executed for other filetypes, you can change the autocommands. For example, if you want to add python files, you could change*.cto*.c,*.py.