better installation of missing packages

  Consolidated some repeated logic into `starter-kit-install-if-needed'.

Author: eschulte

starter-kit-misc.org

@@ -11,9 +11,7 @@ Things that don't fit anywhere else.
 Determine whether required packages are installed. If not, use ELPA to
 install them. Other dependencies are provided by Emacs 24.
 #+begin_src emacs-lisp
-  (dolist (package '(magit))
-    (unless (or (starter-kit-loadable-p package) (package-installed-p package))
-      (package-install package)))
+  (starter-kit-install-if-needed 'magit)
 #+end_src
 
 ** Color Themes

starter-kit-publish.org

@@ -19,10 +19,8 @@ the documentation for the Starter Kit to html.
         (package-archives '(("original"    . "http://tromey.com/elpa/"))))
     ;; load up htmlize
     (package-initialize)
-    (let ((package 'htmlize))
-      (unless (or (member package package-activated-list)
-                  (functionp package))
-        (package-install package)))
+    (unless (functionp 'htmlize)
+      (starter-kit-install-if-needed 'htmlize))
     (require 'htmlize)
     (org-export-htmlize-generate-css)
     ;; define the org-publish-project for the starter kit

starter-kit-python.org

@@ -12,9 +12,7 @@ Support for the Python programming language.
 Determine whether required packages are installed. If not, use ELPA to
 install them.
 #+begin_src emacs-lisp
-  (dolist (package '(python-mode ipython))
-    (unless (or (starter-kit-loadable-p package) (package-installed-p package))
-      (package-install package)))
+  (starter-kit-install-if-needed 'python-mode 'ipython)
 #+end_src
 
 ** Use Python's python-mode.el instead of Emacs' python.el

starter-kit-ruby.org

@@ -24,9 +24,7 @@ Support for the [[http://www.ruby-lang.org/en/][Ruby]] dynamic, open-source prog
 
 ** Yaml mode
 #+begin_src emacs-lisp
-  (dolist (package '(yaml-mode))
-    (unless (or (starter-kit-loadable-p package) (package-installed-p package))
-      (package-install package)))
+  (starter-kit-install-if-needed 'yaml-mode)
   (require 'yaml-mode)
   (add-to-list 'auto-mode-alist '("\\.ya?ml$" . yaml-mode))
 #+end_src

starter-kit-yasnippet.org

@@ -11,12 +11,7 @@ inspired by TextMate's templating syntax.
 
 Install yasnippet.
 #+begin_src emacs-lisp
-  (unless (or (null starter-kit-packages) package-archive-contents)
-        (package-refresh-contents))
-
-  (let ((package 'yasnippet))
-    (unless (or (starter-kit-loadable-p package) (package-installed-p package))
-      (package-install package)))
+  (starter-kit-install-if-needed 'yasnippet)
 
   ;; If `yasnippet-bundle' has previously been installed through ELPA,
   ;; delete it before installing the new `yasnippet'

starter-kit.org

@@ -291,11 +291,15 @@ interested in the actual code implementing the starter kit.
     (defvar starter-kit-packages nil
       "Libraries that should be installed by default (currently none).")
 
-    (unless (or (null starter-kit-packages) package-archive-contents)
-      (package-refresh-contents))
-    (dolist (package starter-kit-packages)
-      (unless (or (starter-kit-loadable-p package) (package-installed-p package))
-        (package-install package)))
+    (defun starter-kit-install-if-needed (&rest packages)
+      "Install PACKAGES using ELPA if they are not loadable or installed locally."
+      (when packages
+        (unless package-archive-contents
+          (package-refresh-contents))
+        (dolist (package packages)
+          (unless (or (starter-kit-loadable-p package)
+                      (package-installed-p package))
+            (package-install package)))))
   #+end_src
 
 - Function for loading other parts of the starter kit