lib/hashformer/generate.rb in hashformer-0.2.1 vs lib/hashformer/generate.rb in hashformer-0.2.2

@@ -119,15 +119,34 @@
         "#{self.class.name}: #{@calls.map{|c| c[:name]}}"
       end
       alias inspect to_s
     end
 
-    # TODO: Add a constant generator (that can be chained?)
+    # Internal representation of a constant output value.  Do not instantiate
+    # directly; call Hashformer::Generate.const (or HF::G.const) instead.
+    class Constant
+      attr_reader :value
 
+      def initialize(value)
+        @value = value
+      end
+    end
+
+
+    # Generates a transformation that always returns a constant value.
+    #
+    # Examples:
+    #   HF::G.const(5)
+    def self.const(value)
+      Constant.new(value)
+    end
+
     # Generates a transformation that passes one or more values from the input
     # Hash (denoted by key names or paths (see Hashformer::Generate.path) to
     # the block.  If the block is not given, then the values are placed in an
     # array in the order in which their keys were given as parameters.
+    #
+    # You can also pass a Hashformer transformation Hash as one or more keys.
     #
     # Examples:
     #   HF::G.map(:first, :last) do |f, l| "#{f} #{l}".strip end
     #   HF::G.map(:a1, :a2) # Turns {a1: 1, a2: 2} into [1, 2]
     #   HF::G.map(HF::G.path[:address][:line1], HF::G.path[:address][:line2])