Tip #812: Keep modified [+] flag after writing to a file

I have seen this being asked in vim mailing list several times, including the recent one which suggested that it should work this way when 'cp' is reset. Basically what happens is that when you modify a file and write contents to a different file, Vim resets the 'modified' flag, which is a Vi compatible behavior. For those who don't want the 'modified' flag reset, the suggested alternative is to use :saveas command instead of :write command, but this changes the name of the current buffer rather than what is wanted. So I have cooked up the following solution which seems to work for regular files, but it is not a fool proof mechanism. The problem is plugins like netrw that catch the event that is triggered when you try to write contents to a different file, and the below solution also uses the same mechanism, so it would end up getting triggered unexpectedly (actually, netrw might work just fine, but you would get ugly error messages in addition).

I have provided a simple workaround for taking care of at least netrw. Basically, it checks if netrw would react to the event and if so skip itself. A more sophisticated solution would actually parse the output of ":au BufWriteCmd" and automatically check if there are other event handlers for this file, but there are not all that many plugins that take advantage of this event (actually I am aware of only netrw), so the workaround should be sufficient (actually, I haven't tested the netrw filenames, so I am not sure it would work). What you should do is to run the ":au BufWriteCmd" before installing this solution and see what other autocommands exist, other than those that are for netrw. You will have to then tweek the code that returns early from the BufWrite() function.

OK, enough said, the solution follows. You basically put the below code in your vimrc and your :write's will work as expected (ie., as described at the start).

----------cut here-----------
function! SetBufWriteAuEnabled(enabled)
  aug BufWrite
  au!
  if a:enabled
    au BufWriteCmd * :call BufWrite()
  endif
  aug END
endfunction
call SetBufWriteAuEnabled(1)

function! BufWrite()
  let fileName = expand('<afile>')
  " If the filename already matches netrw's criteria, then don't do anything.
  if fileName =~ 'ftp://\|rcp://\|scp://\|dav://\|rync://\|sftp://'
    return
  endif
  let _modifiable = &modified;
  exec 'w'.(v:cmdbang?'!':'') v:cmdarg fileName
  let &modified; = _modifiable
endfunction
----------cut here-----------

Enjoy,
Hari

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