built a nifty, useful error message thingy

lib/squib/api/background.rb

@@ -1,15 +0,0 @@
-require_relative '../args/card_range'
-require_relative '../args/draw'
-
-module Squib
-  class Deck
-
-    # DSL method. See http://squib.readthedocs.io
-    def background(opts = {})
-      range = Args::CardRange.new(opts[:range], deck_size: size)
-      draw  = Args::Draw.new(custom_colors).load!(opts, expand_by: size, layout: layout, dpi: dpi)
-      range.each { |i| @cards[i].background(draw.color[i]) }
-    end
-
-  end
-end

lib/squib/deck.rb

@@ -33,7 +33,7 @@ module Squib
                           :img_dir, :prefix, :text_hint, :typographer
     # :nodoc:
     # @api private
-    attr_reader :layout, :conf, :dpi, :font
+    attr_reader :layout, :conf, :dpi, :font, :caller_loc
 
     #
     # deck.size is really just @cards.size
@@ -69,6 +69,7 @@ module Squib
       @height        = Args::UnitConversion.parse height, dpi
       cards.times{ |i| @cards << Squib::Card.new(self, @width, @height, i) }
       @layout = LayoutParser.new(dpi).load_layout(layout)
+      @caller_loc = caller_locations[0] # useful for error messages
       enable_groups_from_env!
       if block_given?
         instance_eval(&block) # here we go. wheeeee!
@@ -102,7 +103,7 @@ module Squib
     ##################
     ### PUBLIC API ###
     ##################
-    require_relative 'api/background'
+    require_relative 'dsl/background'
     require_relative 'api/data'
     require_relative 'api/groups'
     require_relative 'api/image'

lib/squib/dsl/background.rb

@@ -0,0 +1,35 @@
+require_relative '../errors_warnings/warn_unexpected_params'
+module Squib
+  class Deck
+    def background(opts = {}) # DSL method. See http://squib.readthedocs.io
+      BackgroundDSLMethod.new(self).run(opts)
+    end
+  end
+
+  class BackgroundDSLMethod
+    include WarnUnexpectedParam
+
+    def initialize(deck)
+      @error_cxt = <<~EOS.split("\n").join(' ').strip
+        to Squib method '#{caller_locations[1].label}'
+        from #{caller_locations[2].path}:#{caller_locations[2].lineno}
+      EOS
+      @deck = deck
+    end
+
+    def accepted_params
+      [
+        :range,
+        :color
+      ]
+    end
+
+
+    def run(opts)
+      warn_unexpected_params(opts)
+      range = Args::CardRange.new(opts[:range], deck_size: @deck.size)
+      draw  = Args::Draw.new(@deck.custom_colors).load!(opts, expand_by: @deck.size, layout: @deck.layout, dpi: @deck.dpi)
+      range.each { |i| @deck.cards[i].background(draw.color[i]) }
+    end
+  end
+end

lib/squib/errors_warnings/warn_unexpected_params.rb

@@ -0,0 +1,12 @@
+require_relative 'caller_finder'
+
+module Squib::WarnUnexpectedParam
+  def warn_unexpected_params(opts)
+    unexpected = opts.keys - accepted_params
+    unexpected.each do |key|
+      Squib.logger.warn do
+        "Unexpected option '#{key}' #{@error_cxt} ...ignoring"
+      end
+    end
+  end
+end