How to configure Emacs to autoload modes?

[Peter Wu <peterwu@hotmail.com>]

Hello,

I downloaded the python-mode.el to lisp dir and did the byte-compile-file
successsfully. I need to add the following line in my .emacs file so that
when I open or new a Python file, Emacs will load the python-mode for me.

;; Load python-mode
(autoload 'python-mode "python-mode" "Python editing mode" t)
(setq auto-mode-alist (append '(("\\.py$" . python-mode)) auto-mode-alist))

However, I notice that if I create a XML or Perl file, I don't need to add
some similar code in the .emacs file and Emacs can do the job correctly. I
think there must be some settings that configure Emacs to offer such
functionality. Can anyone show me how to do this? Thanks!


--
Peter Wu