#+TITLE: luxicks Emacs Configuration
This is my configuration for the emacs editor.

Points of intrest:
- Personal information (name, email) are stored in a separate ~personal.el~ file.
- Machine specific settings are stored in a separate ~custom.el~ file.
- Both files are loaded automatically.
- When Exporting HTML from ~org-mode~ the style from the ~org-theme.css~ file is inlined automatically.
* Set up ~use-package~
State that we will need package support and define a macro for adding package repos to the archives
#+BEGIN_SRC emacs-lisp
  (require 'package)
  (defmacro append-to-list (target suffix)
    "Append SUFFIX to TARGET in place."
    `(setq ,target (append ,target ,suffix)))

  ;; add to the package repos
  (append-to-list package-archives
                  '(("melpa" . "http://melpa.org/packages/")
                    ("org-elpa" . "https://orgmode.org/elpa/")))
  (package-initialize)
  (unless (package-installed-p 'use-package)
    (package-refresh-contents)
    (package-install 'use-package))

  (require 'use-package)
  (setq use-package-always-ensure t)
  (use-package gnu-elpa-keyring-update)
#+END_SRC

* Fix defaults
** Hide UI elements
Remove all those UI elements. They do not look good and waste space.
#+BEGIN_SRC emacs-lisp
  (tool-bar-mode -1)
  (menu-bar-mode -1)
  (scroll-bar-mode -1)
  (tooltip-mode -1)
  (fringe-mode -1)
#+END_SRC
** Disable file backups
Emacs, loves to clutter directories with backup files.
#+BEGIN_SRC emacs-lisp
  (setq make-backup-files nil)
  (setq auto-save-default nil)
  (setq create-lockfiles nil)
#+END_SRC
** Other settings
#+begin_src emacs-lisp
  ;; The default encoding should be utf-8 everywhere
  (prefer-coding-system 'utf-8)

  ;; All "Yes or No" questions can be shortend to "y or n".
  (defalias 'yes-or-no-p 'y-or-n-p)

  ;; No more startup messages and screens
  (setq inhibit-startup-screen t)
  (setq initial-scratch-message nil)
  (defun display-startup-echo-area-message ()
    (message "Welcome Back!"))

  ;; Highlight matching braces
  (show-paren-mode t)

  ;; cua-mode. Like any other editor
  (cua-mode t)

  ;; Configure the cursor
  (setq-default
   cursor-type 'bar
   indent-tabs-mode nil
   cursor-in-non-selected-windows nil)

  ;; Default column with
  (set-fill-column 95)

  ;; Start up in the home directory
  (setq default-directory "~/")

  ;; Make C-k always kill the whole line
  (setq kill-whole-line t)

  ;; Do not ding. Ever.
  (setq ring-bell-function 'ignore)

  ;; Dialogues always go in the modeline.
  (setq  use-dialog-box nil)
#+end_src
** Keybindings
#+BEGIN_SRC emacs-lisp
  (bind-key "C-x k"      'kill-buffer-with-prejudice)
  (bind-key "C-x C-k"    'kill-buffer-and-window)
  (bind-key "M-p"        'switch-to-previous-buffer)
  (bind-key "M-i"        'delete-indentation)
  (bind-key "C-+"        'text-scale-increase)
  (bind-key "C--"        'text-scale-decrease)
  ;; buffer-list is not a good default
  (bind-key "C-x C-b"    'ibuffer)
  (bind-key "C-c n"      'display-line-numbers-mode)
#+END_SRC

Unbind useless keys.
#+BEGIN_SRC emacs-lisp
     (unbind-key "C-<tab>") ;; prevent switching to tab mode randomly
     (unbind-key "C-h n")   ;; I have never wanted to see emacs news ever
     (unbind-key "C-h C-n") ;; why on earth is it bound to two keybindings??
     (unbind-key "C-x C-d") ;; list-directory is utterly useless given the existence of dired
     (unbind-key "C-x C-r") ;; as is find-file-read-only
#+END_SRC
* Useful functions
** Edit the config file
A simple funtion to open this file for quick editing.
#+BEGIN_SRC emacs-lisp
     (defun edit-config ()
       (interactive)
       (find-file "~/.emacs.d/README.org"))
#+END_SRC
** Reformat a whole buffer
Reindet the whole buffer with ~F12~
#+BEGIN_SRC emacs-lisp
     (defun indent-buffer ()
           (interactive)
           (save-excursion
             (indent-region (point-min) (point-max) nil)))
         (global-set-key [f12] 'indent-buffer)
#+END_SRC
** Split windows and immediately switch to it
#+BEGIN_SRC emacs-lisp
     (defun split-right-and-enter ()
       "Split the window to the right and enter it."
       (interactive)
       (split-window-right)
       (other-window 1))
    (bind-key "C-c 3"      'split-right-and-enter)

     (defun split-below-and-enter ()
       "Split the window down and enter it."
       (interactive)
       (split-window-below)
       (other-window 1))
    (bind-key "C-c 2"      'split-below-and-enter)
#+END_SRC
** Quick buffer switching
#+BEGIN_SRC emacs-lisp
     (defun switch-to-previous-buffer ()
       "Switch to previously open buffer.  Repeated invocations toggle between the two most recently open buffers."
       (interactive)
       (switch-to-buffer (other-buffer (current-buffer) 1)))
#+END_SRC
* Theming
Apply a nice looking theme.
#+BEGIN_SRC emacs-lisp
  ;; Light Theme
  (use-package modus-operandi-theme)
  (load-theme 'modus-operandi t)

  ;; Syntax highlighing
  (setq modus-operandi-theme-faint-syntax t)

  (setq modus-operandi-theme-org-blocks "greyscale")

  (setq default-frame-alist
        (append (list '(width  . 90) '(height . 50)
                      '(vertical-scroll-bars . nil)
                      '(internal-border-width . 10)
                      '(font . "Roboto Mono Light 10"))))
#+END_SRC

Use a nice looking modeline package
#+BEGIN_SRC emacs-lisp
  (use-package telephone-line)
  (telephone-line-mode 1)
#+END_SRC
* Ivy
Use Ivy to make minibuf promts better. Adds the ability to sort and filter.
** Use Ivy
#+BEGIN_SRC emacs-lisp
  (use-package ivy
    :diminish
    :init
    (ivy-mode 1)
    (unbind-key "S-SPC" ivy-minibuffer-map)
    (setq ivy-height 30
          ivy-use-virtual-buffers t
          ivy-use-selectable-prompt t)
    :bind (("C-x b"   . ivy-switch-buffer)
           ("C-c C-r" . ivy-resume)
           ("C-s"     . swiper)))

  ;; ivy-rich makes Ivy look a little bit more like Helm.
  (use-package ivy-rich
    :after counsel
    :custom
    (ivy-virtual-abbreviate 'full
                            ivy-rich-switch-buffer-align-virtual-buffer t
                            ivy-rich-path-style 'abbrev)
    :init
    (ivy-rich-mode))

  (use-package ivy-hydra)
#+END_SRC

** Smex
Sort commands by recency in ivy windows
#+BEGIN_SRC emacs-lisp
  (use-package smex)
#+END_SRC

* Counsel
#+BEGIN_SRC emacs-lisp
  (use-package counsel
    :after ivy
    :init (counsel-mode 1)
    :bind (("C-c ;" . counsel-M-x)
           ("C-c U" . counsel-unicode-char)
           ("C-c i" . counsel-imenu)
           ("C-x f" . counsel-find-file)
           ("C-c y" . counsel-yank-pop)
           ("C-c r" . counsel-recentf)
           :map ivy-minibuffer-map
           ("C-r" . counsel-minibuffer-history))
    :diminish)
#+END_SRC

* Magit
Magit is THE go to package for using git in emacs.
#+BEGIN_SRC emacs-lisp
    (use-package magit
      :bind (("C-c g" . magit-status))
      :diminish magit-auto-revert-mode
      :diminish auto-revert-mode
      :custom
      (magit-remote-set-if-missing t)
      (magit-diff-refine-hunk t)
      :config
      (magit-auto-revert-mode t)
      (advice-add 'magit-refresh :before #'maybe-unset-buffer-modified)
      (advice-add 'magit-commit  :before #'maybe-unset-buffer-modified)
      (setq magit-completing-read-function 'ivy-completing-read)
      (add-to-list 'magit-no-confirm 'stage-all-changes))

    (use-package libgit
      :disabled
      :after magit)
#+END_SRC
The ~advice-add~ entries are thereto stop magit from bugging us to save buffers when commiting and refreshing.

** Helper Functions
#+BEGIN_SRC emacs-lisp
     (autoload 'diff-no-select "diff")
     (defun current-buffer-matches-file-p ()
       "Return t if the current buffer is identical to its associated file."
       (when (and buffer-file-name (buffer-modified-p))
         (diff-no-select buffer-file-name (current-buffer) nil 'noasync)
         (with-current-buffer "*Diff*"
           (and (search-forward-regexp "^Diff finished \(no differences\)\." (point-max) 'noerror) t))))
#+END_SRC

Clear modified bit on all unmodified buffers
#+BEGIN_SRC emacs-lisp
     (defun maybe-unset-buffer-modified (&optional _)
       (interactive)
       (dolist (buf (buffer-list))
         (with-current-buffer buf
           (when (and buffer-file-name (buffer-modified-p) (current-buffer-matches-file-p))
             (set-buffer-modified-p nil)))))

#+END_SRC

Don't prompt to save unmodified buffers on exit.
#+BEGIN_SRC emacs-lisp
     (advice-add 'save-buffers-kill-emacs :before #'maybe-unset-buffer-modified)
#+END_SRC

#+BEGIN_SRC emacs-lisp
     (defun kill-buffer-with-prejudice (&optional _)
       "Kill a buffer, eliding the save dialogue if there are no diffs."
       (interactive)
       (when (current-buffer-matches-file-p) (set-buffer-modified-p nil))
       (kill-buffer))
#+END_SRC

* Org Mode
** Define important files
*** The Link Dump
I use a single file to dump all links I plan on viewing later.
#+BEGIN_SRC emacs-lisp
  (defvar link-dump "")

  (defun open-link-dump ()
    (interactive)
    (find-file link-dump))
#+END_SRC
** Configure org-mode
This is the main configuration for the infamous org-mode.
The most important parts are configuring key bindings to quickly access the files we have defined above.
#+BEGIN_SRC emacs-lisp
  (use-package org
    ;; Always get this from the GNU archive.
    :pin gnu
    :bind (("C-c o c"  . org-capture)
           ("C-c o l"  . open-link-dump)
           ("C-c o s"  . org-store-link)
           ("C-c o a"  . org-agenda)
           :map org-mode-map
           ("M-s-<return>" . org-insert-todo-heading)
           ("M-<return>" . org-insert-heading-respect-content)
           ("C-c c"    . org-mode-insert-code)
           ("C-c a s"  . org-emphasize)
           ("C-c a r"  . org-ref)
           ("C-c a e"  . outline-show-all)
           ("C-c a t"  . unindent-by-four)
           ("C-c -"    . org-edit-special))
    :hook ((org-mode . visual-line-mode)
           (org-mode . variable-pitch-mode)
           (org-mode . org-indent-mode))
    :config
    (let ((todo-path (expand-file-name "~/Notes/todo.org")))
      (when (file-exists-p todo-path)
        (setq org-agenda-files (list todo-path)
              org-default-notes-file todo-path)))

    (setq org-footnote-section ""
          org-startup-with-inline-images t
          org-pretty-entities t
          org-indent-mode t
          org-footnote-section nil
          org-hide-leading-stars nil
          org-link-file-path-type 'relative
          org-image-actual-width nil           ; with this image sizes can be set per image, with an attribute
          org-display-inline-images t
          org-hide-emphasis-markers t
          )
    (setcar (nthcdr 4 org-emphasis-regexp-components) 4)

    (defun org-mode-insert-code ()
      (interactive)
      (org-emphasize ?~)))
#+END_SRC

** Set default archive location
When archiving items in org files, the default ist to crate a separate file named ~<filename>.org_archive~.
This clutters up my notes folder quite a bit, as I use a lot of separate files with thier respective archives.
All archives should be stored in a single  ~.archive~ file per directory.
#+BEGIN_SRC emacs-lisp
  (setq org-archive-location "./.archive::* From %s")
#+END_SRC
** Beautify org-mode
*** Icons
#+BEGIN_SRC emacs-lisp
  (use-package org-bullets
    :init (add-hook 'org-mode-hook (lambda () (org-bullets-mode 1))))

  (setq org-bullets-bullet-list '("◉" "○" "◆" "✿" "✚" "▶"))
#+END_SRC

Ellipsis icon:
#+BEGIN_SRC emacs-lisp
  (setq org-ellipsis "▾")
#+END_SRC

Nice Icons for lists:
#+BEGIN_SRC emacs-lisp
  (add-hook 'org-mode-hook
            (lambda ()
              "Beautify Org Checkbox Symbol"
              (push '("[ ]" . "☐") prettify-symbols-alist)
              (push '("[X]" . "☑" ) prettify-symbols-alist)
              (push '("[-]" . "❍" ) prettify-symbols-alist)
              (prettify-symbols-mode)))
#+END_SRC

We also want them in exported HTML files
#+BEGIN_SRC emacs-lisp
  (setq org-html-checkbox-type 'html)
#+END_SRC

*** Strike out done ckeckbox items
#+BEGIN_SRC emacs-lisp
      (defface org-checkbox-done-text
        '((t (:foreground "#71696A" :strike-through t)))
        "Face for the text part of a checked org-mode checkbox.")

      (font-lock-add-keywords
       'org-mode
       `(("^[ \t]*\\(?:[-+*]\\|[0-9]+[).]\\)[ \t]+\\(\\(?:\\[@\\(?:start:\\)?[0-9]+\\][ \t]*\\)?\\[\\(?:X\\|\\([0-9]+\\)/\\2\\)\\][^\n]*\n\\)"
          1 'org-checkbox-done-text prepend))
       'append)
#+END_SRC

*** Replace dash in bullet lists with unicode symbol
#+BEGIN_SRC emacs-lisp
  (font-lock-add-keywords 'org-mode
                          '(("^ *\\([-]\\) "
                             (0 (prog1 () (compose-region (match-beginning 1) (match-end 1) "•"))))))
#+END_SRC

*** Prettier Timestamps in Exports
#+BEGIN_SRC emacs-lisp
     (setq-default org-display-custom-times t)
     (setq org-time-stamp-custom-formats
           '("<%a %d.%m.%Y>" . "<%d.%m.%y %H:%M>"))
#+END_SRC
** Templates
*** Babel
Here we set custom templates to be used for structure expansion.
These are used when we type "<" folowed by the shortcut for a template and hit "TAB".
e.g. "<s TAB" expands to ~#+BEGIN_SRC ?\n\n#+END_SRC~

Use ~org-tempo~ to quickly insert the structures
#+begin_src emacs-lisp
  (require 'org-tempo)
#+end_src
**** emacs-lisp
Shortcut for creating ~emacs-lisp~ code blocks. This is used extensively in this very file.
#+BEGIN_SRC emacs-lisp
  (add-to-list 'org-structure-template-alist '("el" . "src emacs-lisp"))
#+END_SRC
*** Capture Support Functions
First we define a function to look the subheading under which we want to file captures:
#+BEGIN_SRC emacs-lisp
  (defun org-get-target-headline (&optional targets prompt)
    "Prompt for a location in an org file and jump to it.

  This is for promping for refile targets when doing captures.
  Targets are selected from `org-refile-targets'. If TARGETS is
  given it temporarily overrides `org-refile-targets'. PROMPT will
  replace the default prompt message.

  If CAPTURE-LOC is is given, capture to that location instead of
  prompting."
    (let ((org-refile-targets (or targets org-refile-targets))
          (prompt (or prompt "Capture Location")))
      (org-refile t nil nil prompt))
    )
#+END_SRC

*** Org Capture
Here we define templates we want to use to quickly capture stuff and automatically file them away.
#+BEGIN_SRC emacs-lisp
  (setq org-capture-templates
        '(("l" "Link" entry (file link-dump)
           "* NEW %?\n:PROPERTIES:\n:CREATED: %U\n:END:\n%i\n")
          ))
#+END_SRC

** CSS inlining
Auto inline a CSS theme for org HTML exports.
This will make sure a self contained single HTML file is created.

#+BEGIN_SRC emacs-lisp
  (defun my-org-inline-css-hook (exporter)
    "Insert custom inline css"
    (when (eq exporter 'html)
      (let* ((dir (ignore-errors (file-name-directory (buffer-file-name))))
             (path (concat dir "style.css"))
             (homestyle (or (null dir) (null (file-exists-p path))))
             (final (if homestyle "~/.emacs.d/org-theme.css" path))) ;; <- set your own style file path
        (setq org-html-head-include-default-style nil)
        (setq org-html-head (concat
                             "<style type=\"text/css\">\n"
                             "<!--/*--><![CDATA[/*><!--*/\n"
                             (with-temp-buffer
                               (insert-file-contents final)
                               (buffer-string))
                             "/*]]>*/-->\n"
                             "</style>\n")))))

  (add-hook 'org-export-before-processing-hook 'my-org-inline-css-hook)
#+END_SRC
** Export to a subdirectory
This snippet will create a sub dir for exports from org-mode.
[[https://stackoverflow.com/questions/9559753/emacs-org-mode-export-to-another-directory][See the Stackoverflow question]]

#+BEGIN_SRC emacs-lisp
  (defun org-export-output-file-name-modified (orig-fun extension &optional subtreep pub-dir)
    (unless pub-dir
      (setq pub-dir "Exports")
      (unless (file-directory-p pub-dir)
        (make-directory pub-dir)))
    (apply orig-fun extension subtreep pub-dir nil))
  (advice-add 'org-export-output-file-name :around #'org-export-output-file-name-modified)
#+END_SRC
* Treemacs
Treemacs makes navigating folders and files much easier. This is the default config from [[https://github.com/Alexander-Miller/treemacs][the offical repository]] as a base, with slight modifications to suite my config.

#+BEGIN_SRC emacs-lisp
    (use-package treemacs
      :defer t
      :init
      (with-eval-after-load 'winum
        (define-key winum-keymap (kbd "M-0") #'treemacs-select-window))
      :config
      (progn
        (setq treemacs-collapse-dirs                 (if treemacs-python-executable 3 0)
              treemacs-deferred-git-apply-delay      0.5
              treemacs-display-in-side-window        t
              treemacs-eldoc-display                 t
              treemacs-file-event-delay              5000
              treemacs-file-follow-delay             0.2
              treemacs-follow-after-init             t
              treemacs-git-command-pipe              ""
              treemacs-goto-tag-strategy             'refetch-index
              treemacs-indentation                   2
              treemacs-indentation-string            " "
              treemacs-is-never-other-window         nil
              treemacs-max-git-entries               5000
              treemacs-missing-project-action        'ask
              treemacs-no-png-images                 nil
              treemacs-no-delete-other-windows       t
              treemacs-project-follow-cleanup        nil
              treemacs-persist-file                  (expand-file-name ".cache/treemacs-persist" user-emacs-directory)
              treemacs-position                      'left
              treemacs-recenter-distance             0.1
              treemacs-recenter-after-file-follow    nil
              treemacs-recenter-after-tag-follow     nil
              treemacs-recenter-after-project-jump   'always
              treemacs-recenter-after-project-expand 'on-distance
              treemacs-show-cursor                   nil
              treemacs-show-hidden-files             t
              treemacs-silent-filewatch              nil
              treemacs-silent-refresh                nil
              treemacs-sorting                       'alphabetic-desc
              treemacs-space-between-root-nodes      t
              treemacs-tag-follow-cleanup            t
              treemacs-tag-follow-delay              1.5
              treemacs-width                         35)

        (treemacs-follow-mode t)
        (treemacs-filewatch-mode t)
        (treemacs-fringe-indicator-mode t)
        (treemacs-toggle-show-dotfiles)
        (pcase (cons (not (null (executable-find "git")))
                     (not (null treemacs-python-executable)))
          (`(t . t)
           (treemacs-git-mode 'deferred))
          (`(t . _)
           (treemacs-git-mode 'simple))))
      :bind
      (:map global-map
            ("M-0"       . treemacs)
            ("C-x t 1"   . treemacs-delete-other-windows)
            ("C-x t B"   . treemacs-bookmark)
            ("C-x t C-t" . treemacs-find-file)
            ("C-x t M-t" . treemacs-find-tag)))

    (use-package treemacs-magit
      :after treemacs magit
      :ensure t)
#+END_SRC
* Elfeed
[[https://github.com/skeeto/elfeed][Elfeed]] is an RSS reader for emacs.
#+BEGIN_SRC emacs-lisp
  (use-package elfeed
    :bind ("C-x w" . 'elfeed))
#+END_SRC
** Hooks
elfeed can be extended with various hooks for ease of used
*** Auto tag youtube feeds
#+BEGIN_SRC emacs-lisp
  (add-hook 'elfeed-new-entry-hook
            (elfeed-make-tagger :feed-url "youtube\\.com"
                                :add '(video youtube)))
#+END_SRC
*** Do not spam unread tag
#+BEGIN_SRC emacs-lisp
  (add-hook 'elfeed-new-entry-hook
            (elfeed-make-tagger :before "2 weeks ago"
                                :remove 'unread))
#+END_SRC
* Misc packages
** All The Icons
We want to have some nice looking icons
#+BEGIN_SRC emacs-lisp
  (use-package all-the-icons)
#+END_SRC
** Recentf
Show recent files in the buffer selection
#+BEGIN_SRC emacs-lisp
  (use-package recentf
    :init (recentf-mode t)
    :config
    (add-to-list 'recentf-exclude "\\.emacs.d")
    (add-to-list 'recentf-exclude ".+tmp......\\.org"))
#+END_SRC
** Rainbow Delimiters
We want to have some nicely colored delimiters when reading and writing lisp code
#+BEGIN_SRC emacs-lisp
  (use-package rainbow-delimiters
    :hook (prog-mode . rainbow-delimiters-mode))
#+END_SRC
** Markdown Mode
#+BEGIN_SRC emacs-lisp
  (use-package markdown-mode
    :mode ("\\.md$" . gfm-mode)
    :config
    (when (executable-find "pandoc")
      (setq markdown-command "pandoc -f markdown -t html")))
#+END_SRC
** Duplicate Thing
Quick bind to ~C-c u~ to duplicate the current line
#+BEGIN_SRC emacs-lisp
  (use-package duplicate-thing
    :bind (("C-c u" . duplicate-thing)))
#+END_SRC
** ACE Window
Small package to quickly switch tiled windows.
Use ~M-o~ to quickly switch.
#+BEGIN_SRC emacs-lisp
  (use-package ace-window
    :bind (("M-o" . 'ace-window))
    :config
    (custom-set-faces
     '(aw-leading-char-face
       ((t (:inherit ace-jump-face-foreground :height 3.0))))
     ))
#+END_SRC
** htmlize
HTML Exporter for org-mode
#+BEGIN_SRC emacs-lisp
     (use-package htmlize)
#+END_SRC
** Autocompletion
#+BEGIN_SRC emacs-lisp
  (use-package company
    :config
    (global-company-mode))
#+END_SRC
** vterm
[[https://github.com/akermu/emacs-libvterm][vterm]] is a superiour alternative to the integrated eshell, shell or term modes.
The packages only works on linux and reuqires that emacs is compiled with module support (the ~module-file-suffix~ variable will be filled).
#+BEGIN_SRC emacs-lisp
  (if (and (string-equal system-type "gnu/linux")
         (bound-and-true-p module-file-suffix))
      (use-package vterm
        :ensure t
        :config
        (setq vterm-kill-buffer-on-exit t)
        (setq vterm-copy-exclude-prompt t)))
#+End_SRC
** Olivetti
A simple Emacs minor mode for a nice writing environment.
[[https://github.com/rnkn/olivetti][Gihub Link]]
#+BEGIN_SRC emacs-lisp
  (use-package olivetti
    :config
    (setq-default
     olivetti-hide-mode-line t
     olivetti-body-width 90))
#+END_SRC

Auto enable it in text modes

#+BEGIN_SRC emacs-lisp
  (add-hook 'text-mode-hook 'olivetti-mode)
#+END_SRC
** Ag
Ag.el allows you to search using ~ag~ from inside Emacs. You can filter by file type, edit results inline, or find files.

[[https://agel.readthedocs.io/en/latest/index.html][Documentation]]

#+BEGIN_SRC emacs-lisp
(use-package ag)
#+END_SRC
* Programming
** Elisp
Some customization for writing elisp
#+BEGIN_SRC emacs-lisp
     (defun my-elisp-mode-hook ()
       "My elisp customizations."
       (electric-pair-mode 1)
       (add-hook 'before-save-hook 'check-parens nil t)
       (auto-composition-mode nil))

     (add-hook 'emacs-lisp-mode-hook 'my-elisp-mode-hook)
#+END_SRC
* Load additional files
All information about the current user should reside in the ~personal.el~ file.
This file contains personal information like name, email or other identifying information.
This file should contain definitions, that are the same on every device, but sould not be commited to a repository.
#+BEGIN_SRC emacs-lisp
  (setq personal-file "~/.emacs.d/personal.el")
  (load personal-file 'noerror)
#+END_SRC

Load a custom file from the emacs home dir.
This file is specific to the machine emacs runs on.
It conatins customizations and file locations that are machine dependend.
#+BEGIN_SRC emacs-lisp
    (setq custom-file "~/.emacs.d/custom.el")
    (load custom-file 'noerror)
#+END_SRC