Cool Emacs Hacks

I'm an Emacs-guy, have been for a long time. As much as I use vi
from time-to-time, I never could get into modal editing. Despite
having used GNU Emacs as a programmer for years, I still learn cool
Emacs-fu all the time. Here are a few recent findings:

* Useful Emacs commands, from the Reddit community [0]
* Emacs search and replace across files [1]
* Building regular expressions with Emacs [2]

I do a lot of Perl web development, meaning Perl but also CSS, HTML
and Javascript are in the mix, sometimes all in the same file.
Emacs' MMM-mode [3] works really well if you want to color-highlight
the syntax of disparate languages in the same buffer. Here is the
configuration I use in my .emacs:

(add-to-list 'auto-mode-alist '("\\.tmpl\\'" . html-mode))
(add-to-list 'auto-mode-alist '("\\.[sj]?html?\\'" . html-mode))

;; CSS-Mode
(autoload 'css-mode "css-mode")
(add-to-list 'auto-mode-alist '("\\.css\\'" . css-mode))
(setq cssm-indent-function #'cssm-c-style-indenter)
(setq cssm-indent-level '4)

;; javascript-generic-mode
(require 'generic-x)

;; MMM-Mode
(require 'mmm-auto)
(setq mmm-global-mode 'maybe)

;; Set up an mmm group for fancy html editing
(mmm-add-group
 'fancy-html
 '(
         (html-perl-embedded
                :submode cperl-mode
                :face mmm-output-submode-face
                :front "\\[perl\\]"
                :back "\\[/perl\\]")
         (html-css-embedded
                :submode css-mode
                :face mmm-declaration-submode-face
                :front "<style\[^>\]*>"
                :back "</style>")
         (html-css-attribute
                :submode css-mode
                :face mmm-declaration-submode-face
                :front "\\bstyle=\\s-*\""
                :back "\"")
         (html-javascript-embedded
                :submode javascript-generic-mode
                :face mmm-code-submode-face
                :front "<script\[^>\]*>"
                :back "</script>")
         (html-javascript-attribute
                :submode javascript-generic-mode
                :face mmm-code-submode-face
                :front "\\bon\\w+=\\s-*\""
                :back "\"")
   )
)

(add-to-list 'mmm-mode-ext-classes-alist '(html-mode nil fancy-html))

(add-hook 'html-mode-hook 'guess-xhtml-hook t)

(defun guess-xhtml-hook ()
  "Guess whether the current buffer is XHTML."
  (when 
    (save-excursion 
      (search-forward-regexp "<[?]xml\\|//W3C//DTD XHTML" 80 t))
    (html-mode)
    ))


;; xml-mode                                                                     
(autoload 'nxml-mode "nxml-mode" nil t)
(defalias 'xml-mode 'nxml-mode)

(defalias 'perl-mode 'cperl-mode)

(custom-set-variables
 '(cperl-close-paren-offset -4)
 '(cperl-continued-statement-offset 4)
 '(cperl-indent-level 4)
 '(cperl-indent-parens-as-block t)
 '(cperl-tab-always-indent t))

(setq-default indent-tabs-mode nil)

(defun perl-eval (beg end)
  "Run selected region as Perl code"
  (interactive "r")
  (shell-command-on-region beg end "perl"))
(global-set-key "\M-\C-p" 'perl-eval)

[0] http://www.reddit.com/r/programming/comments/8lfx7/what_emacs_commands_do_you_use_most_and_find_most
[1] http://atomized.org/2009/05/emacs-nerdery-search-replace-across-files
[2] http://emacs-fu.blogspot.com/2009/05/building-regular-expression.html
[3] http://mmm-mode.sourceforge.net