Unable to detect filetype which is set forcefully inside a custom plugin

Question

I have following line in my vimrc-

autocmd BufRead,BufNewFile *.COB,*.PCO set filetype=cobol "force filetype as cobol for .COB and .PCO files

And I have put below lines in my custom plugin at the beginning (~/.vim/plugin/cobmods.vim)

if &ft != "cobol"
   finish
endif

I don't want the plugin to load for other filetypes but this code doesn't work. I have tried putting the plugin inside ~/.vim/after/plugin so that it loads last but still it doesn't work.

Is there any different event that I am supposed to use?

Note: I have used below code inside the plugin and it works fine

if expand('%:e') != 'COB' && expand('%:e') != 'PCO'
   finish
endif

But this doesn't look like the right way.

Also note: I can't change filetype.vim to include *.COB & *.PCO as I don't have the adequate rights as this resides in the installation location and not my home directory.

Answer 1

Files in plugin run during Vim startup (regardless of the file you're opening), before setting the file type.

Remove your check of the filetype option and move the file to:

~/.vim/ftplugin/cobol.vim

I'd also recommend reading the contents of :help ftplugin, (in particular the part about setting b:did_ftplugin) and :help new-filetype.

Answer 2

In addition to ft-plugin, you might check out

:h after-directory

It's a big hammer, but it works.

You shouldn't need to do this, however. And your test for ft == 'cobol' shouldn't be needed either, because if you put your ftplugin in ~/.vim/ftplugin/cobol.vim (as recommended above), only files of type 'cobol' will source it.

If you add the autocmd to set the file type for .cob files, it will be set correctly for files ending in .cob. But note that, in my plain out-o-the-box vim in current mint (ubuntu derivative) distribution, the cob extension will be detected without it.

You will need "already sourced" code though. Look at the first few lines of almost any file in $VIMRUNTIME/ftplugin.