Add XDG config support

CHANGELOG.md

@@ -1,3 +1,6 @@
+## Unreleased
+  - Support loading config from `$XDG_CONFIG_HOME/aprc` - #63
+
 ## v1.2.2
   - Support Ruby 3.0 / IRB 1.2.6 - #57
   - Fix FrozenError - #51

README.md

@@ -325,12 +325,13 @@ red text # (it's red)
 ```
 
 ### Setting Custom Defaults ###
-You can set your own default options by creating ``.aprc`` file in your home
-directory. Within that file assign your  defaults to ``AmazingPrint.defaults``.
+You can set your own default options by creating ``aprc`` file in your `$XDG_CONFIG_HOME`
+directory (defaults to `~/.config` if undefined). Within that file assign your defaults
+to ``AmazingPrint.defaults``.
 For example:
 
 ```ruby
-# ~/.aprc file.
+# ~/.config/aprc file.
 AmazingPrint.defaults = {
   :indent => -2,
   :color => {
@@ -340,6 +341,8 @@ AmazingPrint.defaults = {
 }
 ```
 
+The previous `~/.aprc` location is still supported as fallback.
+
 ## Versioning
 
 AmazingPrint follows the [Semantic Versioning](http://semver.org/) standard.

lib/amazing_print/inspector.rb

@@ -159,13 +159,23 @@ def merge_options!(options = {})
       @options.merge!(options)
     end
 
+    def find_dotfile
+      xdg_config_home = File.expand_path(ENV.fetch('XDG_CONFIG_HOME', '~/.config'))
+      xdg_config_path = File.join(xdg_config_home, 'aprc')  # ${XDG_CONFIG_HOME}/aprc
+
+      return xdg_config_path if File.exist?(xdg_config_path)
+
+      # default to ~/.aprc
+      File.join(ENV['HOME'], '.aprc')
+    end
+
     # This method needs to be mocked during testing so that it always loads
     # predictable values
     #---------------------------------------------------------------------------
     def load_dotfile
       return if @@dotfile # Load the dotfile only once.
 
-      dotfile = File.join(ENV['HOME'], '.aprc')
+      dotfile = find_dotfile
       load dotfile if dotfile_readable?(dotfile)
     end