Make buffer modifiable state match file readonly state
From Vim Tips Wiki
created 2006 · complexity intermediate · author Daniel Harding · version 6.0
If a file on disk is read-only, I would prefer that Vim prevent me from modifying it, rather than giving an error message when I try to write out my changes. The modifiable option does exactly this - when off, it prevents changes from being made to the buffer. However, the modifiable option is on by default. Thus I use the following function to keep a buffer's modifiable state in sync with the underlying file's readonly state. It works especially well when the autoread option is enabled.
function UpdateModifiable() if !exists("b:setmodifiable") let b:setmodifiable = 0 endif if &readonly if &modifiable setlocal nomodifiable let b:setmodifiable = 1 endif else if b:setmodifiable setlocal modifiable endif endif endfunction autocmd BufReadPost * call UpdateModifiable()
Why is the
b:setmodifiable variable needed?
autocmd BufReadPost * if &modifiable | setlocal nomodifiable | else | setlocal modifiable | endif
Did you mean:
autocmd BufReadPost * if &readonly | setlocal nomodifiable | else | setlocal modifiable | endif
I think b:setmodifiable is there to set &modifiable only if the &readonly previously triggered the script to set &nomodifiable . So, it will skip files that are &nomodifiable but not &readonly. Is that correct? I don't think that case happens much.
You are right about b:setmodifiable. It is to prevent setting &modifiable when reloading a file that is not &readonly, but which had &nomodifiable set manually. It may be overkill, but it still works correctly.