filetype on or filetype off?

Question

I use the Pathogen plugin for gvim. When configuring I set the following in my vimrc file:

call pathogen#infect()
call pathogen#helptags()
call pathogen#runtime_append_all_bundles()

filetype on  "force reloading *after* pathogen loaded

Now I'm following this tutorial on Youtube by Martin Brochhaus to set up Vim to be useful for Python coding and he suggests the following:

filetype off
filetype plugin indent on
syntax on 

So currently I have filetype on for pathogen but he is suggesting filetype off. What does this line of code do and how should I configure vimrc so Pathogen and Python are both happy?

Answer 1

call pathogen#runtime_append_all_bundles()

is not needed at all: the function is deprecated and not useful anyway.

If you really need to be safe, this is what you should have at the top of your ~/.vimrc:

" turn filetype detection off and, even if it's not strictly
" necessary, disable loading of indent scripts and filetype plugins
filetype off
filetype plugin indent off

" pathogen runntime injection and help indexing
call pathogen#infect()
call pathogen#helptags()

" turn filetype detection, indent scripts and filetype plugins on
" and syntax highlighting too
filetype plugin indent on
syntax on

However, I've had the following for quite a while without any noticeable issue:

call pathogen#infect()
call pathogen#helptags()

filetype plugin indent on
syntax on

Answer 2

The :filetype off is superfluous when immediately followed by :filetype [plugin indent] on (as it turns on filetype detection again, as described at :help filetype-plugin-on); don't blindly trust arbitrary resources on the Internet :-)

You usually want filetype detection (so that a corresponding syntax can be loaded for highlighting (with :syntax on)), and filetype-specific settings (the plugin part), and indentation rules (indent).

The only pitfall with Pathogen is that this should come after the Pathogen initialization, but you've done that right.

Answer 3

filetype on enables filetype detection. Setting filetype plugin or filetype indent to on will turn on filetype detection if it wasn't already anyway. See :help filetype.