1 files changed, 10 insertions, 5 deletions
diff --git a/lib/puppet/parser/functions/validate_re.rb b/lib/puppet/parser/functions/validate_re.rb
index 8033ca3..9c216d8 100644
--- a/lib/puppet/parser/functions/validate_re.rb
+++ b/lib/puppet/parser/functions/validate_re.rb
@@ -1,5 +1,4 @@
 module Puppet::Parser::Functions
-
   newfunction(:validate_re, :doc => <<-'ENDHEREDOC') do |args|
     Perform simple validation of a string against one or more regular
     expressions. The first argument of this function should be a string to
@@ -8,6 +7,9 @@ module Puppet::Parser::Functions
     of the regular expressions match the string passed in, compilation will
     abort with a parse error.
 
+    If a third argument is specified, this will be the error message raised and
+    seen by the user.
+
     The following strings will validate against the regular expressions:
 
         validate_re('one', '^one$')
@@ -17,17 +19,20 @@ module Puppet::Parser::Functions
 
         validate_re('one', [ '^two', '^three' ])
 
+    A helpful error message can be returned like this:
+
+        validate_re($::puppetversion, '^2.7', 'The $puppetversion fact value does not match 2.7')
+
     ENDHEREDOC
-    if args.length != 2 then
-      raise Puppet::ParseError, ("validate_re(): wrong number of arguments (#{args.length}; must be 2)")
+    if (args.length < 2) or (args.length > 3) then
+      raise Puppet::ParseError, ("validate_re(): wrong number of arguments (#{args.length}; must be 2 or 3)")
     end
 
-    msg = "validate_re(): #{args[0].inspect} does not match #{args[1].inspect}"
+    msg = args[2] || "validate_re(): #{args[0].inspect} does not match #{args[1].inspect}"
 
     raise Puppet::ParseError, (msg) unless args[1].any? do |re_str|
       args[0] =~ Regexp.compile(re_str)
     end
 
   end
-
 end