fhwang · February 23, 2010 16:03 · Feb 23, 2010
diff --git a/gistfile1.txt b/gistfile1.txt
@@ -0,0 +1,18 @@
+def read_only_struct(*attrs)
+  c = Class.new
+  eval_me = <<-CLASS_EVAL_OH_NOES
+    def initialize(#{attrs.map { |sym| sym.to_s }.join(', ')})
+      #{attrs.map { |attr| "@#{attr} = #{attr}" }.join("\n")}
+    end
+
+    attr_reader #{attrs.map { |sym| ":#{sym.to_s}" }.join(', ')}
+  CLASS_EVAL_OH_NOES
+  c.class_eval eval_me
+  c
+end
+
+Foo = read_only_struct :bar
+f = Foo.new 'BAR'
+puts "Getter says: #{f.bar}"
+puts "Setter should raise an exception:"
+f.bar = 'BAZ'