Automatically installing a built-in package from MELPA [duplicate]

Question

This post is asking this question more clearly and concisely.

My code contains the following function to install dependencies:

(defun literef-install-packages()
  "Install any missing packages. The code is taken from
`https://stackoverflow.com/a/10093312/2725810'."

  (setq package-list '(org org-ref pdf-tools smooth-scrolling company))

                    ; list the repositories containing them
  (setq package-archives '(("elpa" . "http://tromey.com/elpa/")
               ("gnu" . "http://elpa.gnu.org/packages/")
               ("marmalade" . "http://marmalade-repo.org/packages/")
               ("melpa" . "http://melpa.milkbox.net/packages/")))
  (package-initialize)
  (unless package-archive-contents
    (package-refresh-contents))

  (dolist (package package-list)
    (unless (eq (package-installed-p package) t)
      (when 
      (yes-or-no-p (concat
            "The package " (symbol-name package)
            " is not installed. Install it? "))
    (package-install package)
    (when (eq package 'pdf-tools) (pdf-tools-install))))))

This code installs all the required packages besides org, whose earlier (compared to the version in MELPA) version is built-in. In particular, when I try to evaluate (package-install 'org), I get the message saying that the package is already installed. How do I get around this problem?

Answer 1

The trick is to get the structure describing the version available for installation. The following function does just that:

(defun literef-package-desc(pkg)
  (car (cdr (assq pkg package-archive-contents))))

We can now install org:

(package-install (literef-package-desc 'org) 'dont-select)