How do I configure vim to set softtabs conditionally?

Question

I am now a Python/Ruby polyglot and have a need to switch out values in my .vimrc depending on the filetype I'm using.

I need tabstop=2, softtabstop=2 for Ruby and tabstop=4, softtabstop=4 for Python. My Google-fu has failed as to how to do this. Any ideas on how to detect file extension?

Answer 1

Make sure you have this in your ~/.vimrc:

filetype plugin on

Then create these two files in ~/.vim/ftplugin:

In ~/.vim/ftplugin/python.vim:

setlocal tabstop=4 softtabstop=4 shiftwidth=4 expandtab

In ~/.vim/ftplugin/ruby.vim:

setlocal tabstop=2 softtabstop=2 shiftwidth=2 expandtab

(I added shiftwidth and expandtab because you almost definitely want those as well.)

Vim will detect the file type and then run the appropriate file based on the type. This is nice because it keeps clutter out of your ~/.vimrc. You can do this for any filetype that Vim recognizes. When you're editing a file, you can use :set filetype? to see what kind of file Vim thinks it is.

Answer 2

First, the dirty way:

autocmd FileType ruby   setlocal tabstop=2 softtabstop=2
autocmd FileType python setlocal expandtab tabstop=4 softtabstop=4

You need setlocal to keep those settings from being applied in other buffers.

---

Then, the less dirty way:

augroup filetypes
    autocmd!
    autocmd FileType ruby   setlocal tabstop=2 softtabstop=2
    autocmd FileType python setlocal expandtab tabstop=4 softtabstop=4
augroup END

A named augroup is good for organizing your ~/.vimrc but it can also be enabled/disabled in one go in case of need.

When you reload your ~/.vimrc, which can happen a lot if you tinker a lot, autocmds never replace previous ones: they are added and added and added and it can lead to serious issues. autocmd! removes all the autocmds in the current augroup before adding them back to avoid problems.

---

Then, the clean way:

Add the following lines to ~/.vim/after/ftplugin/ruby.vim:

setlocal tabstop=2
setlocal softtabstop=2

Add the following lines to ~/.vim/after/ftplugin/python.vim:

setlocal expandtab
setlocal tabstop=4
setlocal softtabstop=4

Even when you organize them cleanly and do autocmd! to keep them from piling up, autocmds bound to the FileType event still pose a problem: they replicate Vim's built-in filetype detection mechanism. Assuming you have filetype plugin indent on in your ~/.vimrc, that mechanism already reacts to the FileType of your buffer and tries to source scripts contained in ~/.vim/ftplugin/ and ~/.vim/after/ftplugin/.

That's the most appropriate place for filetype-specific settings.

Answer 3

You need to base it off the file type like this:

au FileType ruby set tabstop=2 softtabstop=2
au FileType python set expandtab tabstop=4 softtabstop=4

That would go in your .vimrc or any file that gets loaded after it.