Move rainbow-identifiers from spacemacs config to syl20bnr

It is a pretty heavy subjective setting so moved it in my
configuration layer and documented it in a readme for this
layer

README.md

@@ -25,7 +25,7 @@
     - [Configuration layers](#configuration-layers)
     - [Contributions](#contributions)
     - [Main principles](#main-principles)
-    - [UI and syntax highlighting](#ui-and-syntax-highlighting)
+    - [UI tweaks](#ui-tweaks)
     - [Commands](#commands)
         - [Return to normal mode](#return-to-normal-mode)
         - [Executing Vim and Emacs commands](#executing-vim-and-emacs-commands)
@@ -99,7 +99,6 @@ to load.
 ## Screenshots
 
 ![src_startup](https://raw.githubusercontent.com/syl20bnr/spacemacs/master/doc/spacemacs_startup.png)
-![scr_python](https://raw.githubusercontent.com/syl20bnr/spacemacs/master/doc/spacemacs.png)
 
 *Note: Even though screenshots are updated frequently, `Spacemacs` is evolving
 quickly and the screenshots may not reflect exactly the current state of the
@@ -167,7 +166,7 @@ few examples:
 - Save all opened buffers: `<SPC> f S`
 - Open (switch) to a buffer with `helm`: `<SPC> b s`
 
-## UI and syntax highlighting
+## UI tweaks
 
 `Spacemacs` has a minimalistic and distraction free UI with a lot of subtle
 customizations which make it unique compared to other Emacs kits:
@@ -179,11 +178,6 @@ customizations which make it unique compared to other Emacs kits:
  - custom fringe bitmaps for [git gutter][git-gutter].
  - dedicated startup page with a mode aimed at easily managing `Spacemacs`
 
-`Spacemacs` syntax highlighting is also different from the majority of other
-Emacs configurations: instead of colorized keywords, `Spacemacs` has *colorized
-variables and functions* using the [rainbow identifiers][rainbow-identifiers]
-mode. Each variable and function has a unique color associated to it.
-
 ## Commands
 
 Every sequences must be performed in `normal` mode.
@@ -834,4 +828,3 @@ Send code to inferior process commands:
 [monokai-theme]: https://github.com/oneKelvinSmith/monokai-emacs
 [zenburn-theme]: https://github.com/bbatsov/zenburn-emacs
 [git-gutter]: https://github.com/syohex/emacs-git-gutter-fringe
-[rainbow-identifiers]: https://github.com/Fanael/rainbow-identifiers

contrib/syl20bnr/funcs.el

@@ -0,0 +1,18 @@
+(defun syl20bnr/tweak-theme-colors (theme)
+  "Tweak color themes by adjusting rainbow-identifiers colors settings an by
+disabling some faces in order to make colored identifiers stand out."
+  (interactive)
+  (pcase theme
+    (`solarized-dark (setq rainbow-identifiers-cie-l*a*b*-saturation 60
+                           rainbow-identifiers-cie-l*a*b*-lightness 50))
+    (`solarized-light (setq rainbow-identifiers-cie-l*a*b*-saturation 100
+                            rainbow-identifiers-cie-l*a*b*-lightness 40))
+    (_ (setq rainbow-identifiers-cie-l*a*b*-saturation 80
+             rainbow-identifiers-cie-l*a*b*-lightness 45)))
+  ;; To make the variables stand out, keyword coloring is disabled
+  ;; (set-face-attribute 'highlight-quoted-symbol nil
+  ;;                     :foreground nil :slant 'normal :weight 'bold)
+  (set-face-attribute 'font-lock-function-name-face nil
+                      :foreground nil :slant 'normal :weight 'normal)
+  (set-face-attribute 'font-lock-keyword-face nil
+                      :foreground nil :slant 'normal :weight 'bold))

contrib/syl20bnr/packages.el

@@ -1 +1,22 @@
-(defvar syl20bnr-packages '())
+(defvar syl20bnr-packages
+  '(
+    rainbow-identifiers
+    )
+  "List of all packages to install and/or initialized. Built-in packages
+which require an initialization must be listed explicitly in the list.")
+
+(defun syl20bnr/init-rainbow-identifiers ()
+  (use-package rainbow-identifiers
+    :commands rainbow-identifiers-mode
+    :init
+    (progn 
+      (setq rainbow-identifiers-choose-face-function 'rainbow-identifiers-cie-l*a*b*-choose-face
+            rainbow-identifiers-cie-l*a*b*-saturation 100
+            rainbow-identifiers-cie-l*a*b*-lightness 40
+            ;; override theme faces
+            rainbow-identifiers-faces-to-override '(highlight-quoted-symbol
+                                                    font-lock-variable-name-face))
+      (add-to-hooks 'rainbow-identifiers-mode '(prog-mode-hook
+                                                erlang-mode-hook)))
+    :config
+    (syl20bnr/tweak-theme-colors 'solarized-light)))

spacemacs/funcs.el

@@ -297,24 +297,7 @@ changed to THEME."
         'flycheck-color-mode-line-info-face nil
         :foreground ml-foreground
         :background ml-background
-        :box (list :line-width 1 :color (face-foreground 'flycheck-fringe-info)))))
-  (eval-after-load "rainbow-identifiers"
-    ;; adjust saturation and lightness of rainbow-delimiters depending on the
-    ;; current theme
-    (pcase theme
-      (`solarized-dark (setq rainbow-identifiers-cie-l*a*b*-saturation 60
-                             rainbow-identifiers-cie-l*a*b*-lightness 50))
-      (`solarized-light (setq rainbow-identifiers-cie-l*a*b*-saturation 100
-                             rainbow-identifiers-cie-l*a*b*-lightness 40))
-      (_ (setq rainbow-identifiers-cie-l*a*b*-saturation 80
-               rainbow-identifiers-cie-l*a*b*-lightness 45))))
-  ;; To make the variables stand out, keyword coloring is disabled
-  ;; (set-face-attribute 'highlight-quoted-symbol nil
-  ;;                     :foreground nil :slant 'normal :weight 'bold)
-  (set-face-attribute 'font-lock-function-name-face nil
-                      :foreground nil :slant 'normal :weight 'normal)
-  (set-face-attribute 'font-lock-keyword-face nil
-                      :foreground nil :slant 'normal :weight 'bold))
+        :box (list :line-width 1 :color (face-foreground 'flycheck-fringe-info))))))
 
 ;; From http://xugx2007.blogspot.ca/2007/06/benjamin-rutts-emacs-c-development-tips.html
 (setq compilation-finish-function

spacemacs/packages.el

@@ -91,7 +91,6 @@
     ;; not working well for now
     ;; rainbow-blocks
     rainbow-delimiters
-    rainbow-identifiers
     rainbow-mode
     rcirc
     rcirc-color
@@ -116,8 +115,7 @@
     zenburn-theme
     )
   "List of all packages to install and/or initialized. Built-in packages
-which require an initialization must be listed explicitly in the list."
-)
+which require an initialization must be listed explicitly in the list.")
 
 ;; Initialization of packages
 
@@ -1313,21 +1311,6 @@ which require an initialization must be listed explicitly in the list."
                                           erlang-mode-hook
                                           )))))
 
-(defun spacemacs/init-rainbow-identifiers ()
-  (use-package rainbow-identifiers
-    :commands rainbow-identifiers-mode
-    :init
-    (progn 
-      (setq rainbow-identifiers-choose-face-function 'rainbow-identifiers-cie-l*a*b*-choose-face
-            rainbow-identifiers-cie-l*a*b*-saturation 100
-            rainbow-identifiers-cie-l*a*b*-lightness 40
-            ;; override theme faces
-            rainbow-identifiers-faces-to-override '(highlight-quoted-symbol
-                                                    font-lock-variable-name-face))
-      (add-to-hooks 'rainbow-identifiers-mode '(prog-mode-hook
-                                                erlang-mode-hook)))
-))
-
 (defun spacemacs/init-rainbow-mode ()
   (use-package rainbow-mode
     :defer t