Vim: Set wrapping and indentation according to file type (Shallow Thoughts)

Akkana's Musings on Open Source Computing, Science, and Nature.

Sun, 15 Jun 2014

Vim: Set wrapping and indentation according to file type

Although I use emacs for most of my coding, I use vim quite a lot too, for quick edits, mail messages, and anything I need to edit when logged onto a remote server. In particular, that means editing my procmail spam filter files on the mail server.

The spam rules are mostly lists of regular expression patterns, and they can include long lines, such as:
gift ?card .*(Visa|Walgreen|Applebee|Costco|Starbucks|Whitestrips|free|Wal.?mart|Arby)

My default vim settings for editing text, including line wrap, don't work if get a flood of messages offering McDonald's gift cards and decide I need to add a "|McDonald" on the end of that long line.

Of course, I can type ":set tw=0" to turn off wrapping, but who wants to have to do that every time? Surely vim has a way to adjust settings based on file type or location, like emacs has.

It didn't take long to find an example of Project specific settings on the vim wiki. Thank goodness for the example -- I definitely wouldn't have figured that syntax out just from reading manuals. From there, it was easy to make a few modifications and set textwidth=0 if I'm opening a file in my procmail directory:

" Set wrapping/textwidth according to file location and type
function! SetupEnvironment()
  let l:path = expand('%:p')
  if l:path =~ '/home/akkana/Procmail'
    " When editing spam filters, disable wrapping:
    setlocal textwidth=0
endfunction
autocmd! BufReadPost,BufNewFile * call SetupEnvironment()

Nice! But then I remembered other cases where I want to turn off wrapping. For instance, editing source code in cases where emacs doesn't work so well -- like remote logins over slow connections, or machines where emacs isn't even installed, or when I need to do a lot of global substitutes or repetitive operations. So I'd like to be able to turn off wrapping for source code.

I couldn't find any way to just say "all source code file types" in vim. But I can list the ones I use most often. While I was at it, I threw in a special wrap setting for mail files:

" Set wrapping/textwidth according to file location and type
function! SetupEnvironment()
  let l:path = expand('%:p')
  if l:path =~ '/home/akkana/Procmail'
    " When editing spam filters, disable wrapping:
    setlocal textwidth=0
  elseif (&ft == 'python' || &ft == 'c' || &ft == 'html' || &ft == 'php')
    setlocal textwidth=0
  elseif (&ft == 'mail')
    " Slightly narrower width for mail (and override mutt's override):
    setlocal textwidth=68
  else
    " default textwidth slightly narrower than the default
    setlocal textwidth=70
  endif
endfunction
autocmd! BufReadPost,BufNewFile * call SetupEnvironment()

As long as we're looking at language-specific settings, what about doing language-specific indentation like emacs does? I've always suspected vim must have a way to do that, but it doesn't enable it automatically like emacs does. You need to set three variables, assuming you prefer to use spaces rather than tabs:

" Indent specifically for the current filetype
filetype indent on
" Set indent level to 4, using spaces, not tabs
set expandtab shiftwidth=4

Then you can also use useful commands like << and >> for in- and out-denting blocks of code, or ==, for indenting to the right level. It turns out vim's language indenting isn't all that smart, at least for Python, and gets the wrong answer a lot of them time. You can't rely on it as a syntax checker the way you can with emacs. But it's a lot better than no language-specific indentation.

I will be a much happier vimmer now!

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[ 11:29 Jun 15, 2014    More linux/editors | permalink to this entry | comments ]
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