Emacs: check for existence for loading, to avoid error.

.emacs.d/plugins.el

@@ -3,7 +3,7 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 ;; User plugin path.
-(add-to-list 'load-path "~/.emacs.d/plugins")
+;; (add-to-list 'load-path "~/.emacs.d/plugins")
 
 ;;==============================================================================
 ;; Yasnippet
@@ -17,8 +17,8 @@
 
 ;; Next follows a traditional, yet not-optimized configuration for Yasnippet.
 ;; (add-to-list 'load-path "/usr/share/emacs/site-lisp/yas")
-(require 'yasnippet) ;; not yasnippet-bundle
-
+(if (require 'yasnippet nil t)
+    (progn
      (setq yas-snippet-dirs "~/.emacs.d/snippets" )
 
      (if (fboundp 'yas/initialize)
@@ -31,8 +31,10 @@
        (progn
          (yas-global-mode 1)
          (yas-load-directory yas-snippet-dirs))
+
        )
 
+     ))
 
 ;;==============================================================================
 ;; Lua
@@ -44,7 +46,15 @@
 ;; MediaWiki
 ;;==============================================================================
 
-(require 'mediawiki)
+(if (require 'mediawiki nil t)
+    (progn
+
+     (setq mediawiki-site-alist
+           '(
+             ("Wikipedia" "http://en.wikipedia.org/w/" "Ambrevar" "" "Main Page")
+             ("Wikibooks" "http://en.wikibooks.org/w/" "Ambrevar" "" "LaTeX")
+             ("ArchLinux" "https://wiki.archlinux.org/" "Ambrevar" "" "Mutt"))
+           )
 
      ;; Macros.
      ;; Use C-( stuff C-) to record a macro.
@@ -57,13 +67,6 @@
      (fset 'ltx-template-source-to-usage
            "\C-@\C-s>\C-w\C-?\C-m\C-w\C-d\C-@\C-s</source\C-m\C-[Od\C-[[D\C-[[D\C-[[D\C-wltxu\C-i\C-y\C-i\C-k\C-k")
 
-(setq mediawiki-site-alist
-      '(
-        ("Wikipedia" "http://en.wikipedia.org/w/" "Ambrevar" "" "Main Page")
-        ("Wikibooks" "http://en.wikibooks.org/w/" "Ambrevar" "" "LaTeX")
-        ("ArchLinux" "https://wiki.archlinux.org/" "Ambrevar" "" "Mutt"))
-      )
-
      ;; The url-cookie timer is set to a high value because it seems that once the
      ;; cookie has been saved, MediaWiki fails to upload files correctly.  Is
      ;; 'url-do-setup' needed to make sure the url-cookie-save-interval variable is
@@ -82,6 +85,8 @@
              ;; (local-set-key (kbd "C-c l U") 'ltx-template-source-to-usage)
              ))
 
+     ))
+
 ;;==============================================================================
 ;; DoxyMacs
 ;;==============================================================================
@@ -101,7 +106,7 @@
 ;;==============================================================================
 ;; Zsh style completion.
 
-(require 'zlc)
+(if (require 'zlc nil t)
     (let ((map minibuffer-local-map))
       ;; Like Zsh menu select.  Should not use arrows directly because it overrides
       ;; default controls like previous entry, or previous/next char.
@@ -110,10 +115,11 @@
       (define-key map (kbd "C-<right>") 'zlc-select-next)
       (define-key map (kbd "C-<left>")  'zlc-select-previous)
 
-  ;;; Reset selection.
+      ;; Reset selection.
       (define-key map (kbd "C-c") 'zlc-reset)
-  )
 
       ;; (setq zlc-select-completion-immediately t)
 
       ;; To change style, M-x customize-face and input zlc-selected-completion-face.
+      )
+)