Does Vim automatically load filetype-specific plugins for custom filetypes?

Question

I understand that the recommended method for defining filetype-specific behavior in Vim is with .vim files and filetype plugin option. To add settings for .html files, for instance, I would add filetype plugin on in my .vimrc and add the settings to ~/.vim/ftplugin/html.vim.

All examples of this method that I can find, however, are about popular existing filetypes like .html or .sql. Would the same fix work for custom-defined file types? Let's say I want to use a new filetype with the extension .newft. If I create ~/.vim/ftplugin/newft.vim with the settings for this new type and load somefile.newft, would Vim automatically detect its type and load newft.vim?

I'm asking this because this is exactly what I'm doing and it's not working so far. I'd like to know whether this is an error or an expected behavior of Vim.

Answer 1

:h new-filetype outlines the different ways to add support for a new filetype.

I recommend method A which is as simple as writing the following in ~/.vim/ftdetect/newft.vim:

autocmd BufRead,BufNewFile  *.newft  set filetype=newft

and letting Vim deal with the rest.

Assuming you have filetype plugin on in your ~/.vimrc, the example above will make Vim try to source ~/.vim/ftplugin/newft.vim each time you read or create a buffer associated with a *.newft file or do :setfiletype newft/:set filetype=newft on an existing buffer.