1 files changed, 36 insertions, 0 deletions
diff --git a/puppet/modules/stdlib/lib/puppet/parser/functions/difference.rb b/puppet/modules/stdlib/lib/puppet/parser/functions/difference.rb
new file mode 100644
index 00000000..cd258f75
--- /dev/null
+++ b/puppet/modules/stdlib/lib/puppet/parser/functions/difference.rb
@@ -0,0 +1,36 @@
+#
+# difference.rb
+#
+
+module Puppet::Parser::Functions
+  newfunction(:difference, :type => :rvalue, :doc => <<-EOS
+This function returns the difference between two arrays.
+The returned array is a copy of the original array, removing any items that
+also appear in the second array.
+
+*Examples:*
+
+    difference(["a","b","c"],["b","c","d"])
+
+Would return: ["a"]
+    EOS
+  ) do |arguments|
+
+    # Two arguments are required
+    raise(Puppet::ParseError, "difference(): Wrong number of arguments " +
+      "given (#{arguments.size} for 2)") if arguments.size != 2
+
+    first = arguments[0]
+    second = arguments[1]
+
+    unless first.is_a?(Array) && second.is_a?(Array)
+      raise(Puppet::ParseError, 'difference(): Requires 2 arrays')
+    end
+
+    result = first - second
+
+    return result
+  end
+end
+
+# vim: set ts=2 sw=2 et :