Ugh, Yaml has a <<: merge key. facepalm: true

README.md

@@ -163,7 +163,7 @@ Working with x-y coordinates all the time can be tiresome, and ideally everythin
 
 To use a layout, set the `layout:` option on a `Deck.new` command to point to a YAML file. Any command that allows a `layout` option can be set with a Ruby symbol or String, and the command will then load the specified `x`, `y`, `width`, and `height`. The individual command can also override these options. 
 
-Note: YAML is very finnicky about having tabs in the file. Use two spaces for indentation instead.
+Note: YAML is very finnicky about having not allowing tabs. Use two spaces for indentation instead. If you get a `Psych` syntax error, this is likely the culprit. Indendation is also strongly enforced in Yaml too. See the [Yaml docs](http://www.yaml.org/YAML_for_ruby.html).
 
 Layouts will override Squib's defaults, but are overriden by anything specified in the command itself. Thus, the order of precedence looks like this:
 
@@ -171,7 +171,17 @@ Layouts will override Squib's defaults, but are overriden by anything specified
 * If anything was not yet specified, use what was given in a layout (if a layout was specified in the command and the file was given to the Deck)
 * If still anything was not yet specified, use what was given in Squib's defaults.
 
-Layouts also allow for a special `extends` field that will copy all of the settings from another entry. Only a single level of extends are supported currently (contact the developer if you want multiple levels). 
+Since Layouts are in Yaml, we have the full power of that data format. One particular feature you should look into are ["merge keys"](http://www.yaml.org/YAML_for_ruby.html#merge_key). With merge keys, you can define base styles in one entry, then include those keys elsewhere. For example:
+
+```sh
+icon: &icon
+  width: 50
+  height: 50
+icon_left
+  <<: *icon
+  x: 100
+# The layout for icon_left will have the width/height from icon!
+```
 
 See the `use_layout` sample found [here](https://github.com/andymeneely/squib/tree/master/samples/)
 
@@ -196,7 +206,7 @@ See the `custom_config` sample found [here](https://github.com/andymeneely/squib
 
 Squib tries to keep you DRY with the following features:
 
-* Custom layouts allow you to specify various arguments in a separate file. This is great for x-y coordinates and alignment properties that would otherwise clutter up perfectly readable code. The `extends` takes this a step further and lets you specify base styles that can then be extended by other styles.
+* Custom layouts allow you to specify various arguments in a separate file. This is great for x-y coordinates and alignment properties that would otherwise clutter up perfectly readable code. Yaml's "merge keys" takes this a step further and lets you specify base styles that can then be extended by other styles.
 * Flexible ranges and array handling: the `range` parameter in Squib is very flexible, meaning that one `text` command can specify different text in different fonts, styles, colors, etc. for each card. If you find yourself doing multiple `text` command for the same field across different ranges of cards, there's probably a better way to condense.
 * Custom colors keep you from hardcoding magic color strings everywhere. Custom colors are entered into the `config.yml` file.
 

lib/squib/deck.rb

@@ -49,7 +49,8 @@ module Squib
     # @param height: [Integer] the height of each card in pixels
     # @param cards: [Integer] the number of cards in the deck
     # @param dpi: [Integer] the pixels per inch when rendering out to PDF or calculating using inches. 
-    # @param config: [String] the file used for global settings of this deck
+    # @param config: [String] the Yaml file used for global settings of this deck
+    # @param layout: [String] the Yaml file used for layouts.
     # @param block [Block] the main body of the script.
     # @api public
     def initialize(width: 825, height: 1125, cards: 1, dpi: 300, config: 'config.yml', layout: nil, &block)
@@ -61,7 +62,7 @@ module Squib
       @progress_bar = Squib::Progress.new(false)
       cards.times{ @cards << Squib::Card.new(self, width, height) }
       load_config(config)
-      load_layout(layout)
+      @layout = YAML.load_file(layout) unless layout.nil?
       if block_given?
         instance_eval(&block)
       end
@@ -98,54 +99,6 @@ module Squib
       end
     end
 
-    # Load the layout configuration file, if exists
-    # @api private
-    def load_layout(file)
-      return if file.nil?
-      @layout = {}
-      yml = YAML.load_file(file)
-      yml.each do |key, value|
-        @layout[key] = recurse_extends(yml, key, {})
-      end
-    end
-
-    # Process the extends recursively
-    # :nodoc:
-    # @api private
-    def recurse_extends(yml, key, visited )
-      assert_not_visited(key, visited)
-      return yml[key] unless has_extends?(yml, key)
-      visited[key] = key
-      parent_keys = [yml[key]['extends']].flatten
-      h = {}
-      parent_keys.each do |parent_key|
-        from_extends = yml[key].merge(recurse_extends(yml, parent_key, visited)) do |key, child_val, parent_val|
-          child_val #child overrides parent when merging 
-        end 
-        h = h.merge(from_extends) do |key, older_sibling, younger_sibling|
-          younger_sibling #when two siblings have the same entry, the "younger" (lower one) overrides
-        end
-      end
-      return h
-    end
-
-    # Does this layout entry have an extends field?
-    # i.e. is it a base-case or will it need recursion?
-    # :nodoc:
-    # @api private
-    def has_extends?(yml, key)
-      yml[key].key?('extends')
-    end
-
-    # Safeguard against malformed circular extends
-    # :nodoc:
-    # @api private
-    def assert_not_visited(key, visited)
-      if visited.key? key
-        raise "Invalid layout: circular extends with '#{key}'"
-      end
-    end
-
     ##################
     ### PUBLIC API ###
     ##################

samples/custom-layout.yml

@@ -18,17 +18,22 @@ subtitle:
   height: 60
   align: !ruby/symbol center
   valign: !ruby/symbol middle
-icon:
+
+# Yaml has this beautfiul feature for us: merge keys
+# http://www.yaml.org/YAML_for_ruby.html#merge_key
+# Define an alias with &foo, then use <<: *foo to include it
+# Everything gets merged, with later merges overriding 
+icon: &icon
   width: 125
   height: 125
   y: 250
 icon_left:
-  extends: icon
+  <<: *icon 
   x: 150
 icon_middle:
-  extends: icon
+  <<: *icon
   x: 350
   y: 400  #overrides the y inherited from icon
 icon_right:
-  extends: icon
+  <<: *icon
   x: 550

spec/data/easy-circular-extends.yml

@@ -1,6 +0,0 @@
-a: 
-  extends: b
-  x: 50
-b:
-  extends: a
-  x: 150

spec/data/hard-circular-extends.yml

@@ -1,9 +0,0 @@
-a: 
-  extends: c
-  x: 50
-b:
-  extends: a
-  x: 150
-c: 
-  extends: b
-  y: 250

spec/data/multi-extends-single-entry.yml

@@ -1,14 +1,13 @@
-aunt: 
+aunt: &aunt
   a: 101
   b: 102
   c: 103
-uncle: 
+uncle: &uncle
   x: 104
   y: 105
   b: 106
 child:
-  extends: 
-    - uncle
-    - aunt
+  <<: *uncle
+  <<: *aunt
   a: 107
   x: 108

spec/data/multi-level-extends.yml

@@ -1,10 +1,10 @@
-frame: 
+frame: &frame
   x: 38
   y: 38
-title:
-  extends: frame
+title: &title
+  <<: *frame
   y: 50
   width: 100
-subtitle:
-  extends: title
+subtitle: 
+  <<: *title
   y: 150

spec/data/pre-extends.yml

@@ -1,7 +0,0 @@
-title:
-  extends: frame
-  y: 50
-  width: 100
-frame: 
-  x: 38
-  y: 38

spec/data/self-circular-extends.yml

@@ -1,3 +0,0 @@
-a: 
-  extends: a
-  x: 50

spec/data/single-extends.yml

@@ -1,7 +1,7 @@
-frame: 
+frame: &frame
   x: 38
   y: 38
 title:
-  extends: frame
+  <<: *frame
   y: 50
   width: 100

spec/data/single-level-multi-extends.yml

@@ -1,12 +1,12 @@
-frame: 
+frame: &frame
   x: 38
   y: 38
 title:
-  extends: frame
+  <<: *frame
   y: 50
   width: 100
 title2:
-  extends: frame
+  <<: *frame
   x: 75
   y: 150
   width: 150

spec/deck_spec.rb

@@ -68,24 +68,6 @@ describe Squib::Deck do
               'y' => 38, 
               },
             'title' => {
-              'extends' => 'frame',
-              'x' => 38, 
-              'y' => 50, 
-              'width' => 100,
-              }
-            }
-          )
-    end
-
-    it "applies the extends regardless of order" do
-      d = Squib::Deck.new(layout: test_file('pre-extends.yml')) 
-      expect(d.layout).to \
-        eq({'frame' => {
-              'x' => 38, 
-              'y' => 38, 
-              },
-            'title' => {
-              'extends' => 'frame',
               'x' => 38, 
               'y' => 50, 
               'width' => 100,
@@ -102,13 +84,11 @@ describe Squib::Deck do
               'y' => 38, 
               },
             'title' => {
-              'extends' => 'frame',
               'x' => 38, 
               'y' => 50, 
               'width' => 100,
               },
             'title2' => {
-              'extends' => 'frame',
               'x' => 75, 
               'y' => 150, 
               'width' => 150,
@@ -131,7 +111,6 @@ describe Squib::Deck do
               'b' => 106, 
               },
             'child' => {
-              'extends' => ['uncle','aunt'],
               'a' => 107, # my own
               'b' => 102, # from the younger aunt
               'c' => 103, # from aunt
@@ -150,13 +129,11 @@ describe Squib::Deck do
               'y' => 38, 
               },
             'title' => {
-              'extends' => 'frame',
               'x' => 38, 
               'y' => 50, 
               'width' => 100,
               },
             'subtitle' => {
-              'extends' => 'title',
               'x' => 38,
               'y' => 150, 
               'width' => 100,
@@ -165,24 +142,6 @@ describe Squib::Deck do
           )
     end
 
-    it "fails on a self-circular extends" do
-      file = test_file('self-circular-extends.yml')
-      expect { Squib::Deck.new(layout: file) }.to \
-        raise_error(RuntimeError, "Invalid layout: circular extends with 'a'")
-    end
-
-    it "fails on a easy-circular extends" do
-      file = test_file('easy-circular-extends.yml')
-      expect { Squib::Deck.new(layout: file) }.to \
-        raise_error(RuntimeError, "Invalid layout: circular extends with 'a'")
-    end
-
-    it "hard on a easy-circular extends" do
-      file = test_file('hard-circular-extends.yml')
-      expect { Squib::Deck.new(layout: file) }.to \
-        raise_error(RuntimeError, "Invalid layout: circular extends with 'a'")
-    end
-
   end
 
 end