Add deprecation function

Author: Domenic Del Nano

lib/puppet/parser/functions/deprecation.rb

@@ -0,0 +1,16 @@
+module Puppet::Parser::Functions
+  newfunction(:deprecation, :doc => <<-EOS
+  Function to print deprecation warnings (this is the 3.X version of it), The uniqueness key - can appear once. The msg is the message text including any positional information that is formatted by the user/caller of the method.).
+EOS
+  ) do |arguments|
+
+    raise(Puppet::ParseError, "deprecation: Wrong number of arguments given (#{arguments.size} for 2)") unless arguments.size == 2
+
+    key = arguments[0]
+    message = arguments[1]
+
+    if ENV['STDLIB_LOG_DEPRECATIONS'] == "true"
+      warning("deprecation. #{key}. #{message}")
+    end
+  end
+end