Emacs Lisp: How to add a folder and all its first level sub-folders to the load-path

Question

If I have a folder structure set up like this:

~/Projects
    emacs
        package1
            package1-helpers
        package2
            package2-helpers
            package2-more-helpers
        package3
            package3-helpers

How do I add these folders:

• ~/Projects/emacs
• ~/Projects/emacs/package1
• ~/Projects/emacs/package2
• ~/Projects/emacs/package3

...to the load-path from my .emacs file?

I basically need a short automated version of this code:

(add-to-list 'load-path "~/Projects/emacs")
(add-to-list 'load-path "~/Projects/emacs/package1")
(add-to-list 'load-path "~/Projects/emacs/package2")
(add-to-list 'load-path "~/Projects/emacs/package3")

Answer 1

(let ((base "~/Projects/emacs"))
  (add-to-list 'load-path base)
  (dolist (f (directory-files base))
    (let ((name (concat base "/" f)))
      (when (and (file-directory-p name) 
                 (not (equal f ".."))
                 (not (equal f ".")))
        (add-to-list 'load-path name)))))

Answer 2

Here's something I use in my .emacs:

(let* ((my-lisp-dir "~/.elisp/")
       (default-directory my-lisp-dir)
       (orig-load-path load-path))
  (setq load-path (cons my-lisp-dir nil))
  (normal-top-level-add-subdirs-to-load-path)
  (nconc load-path orig-load-path))

If you look at the description for normal-top-level-add-subdirs-to-load-path, it's somewhat smart about picking which directories to exclude.