1 files changed, 19 insertions, 14 deletions
diff --git a/lib/puppet/parser/functions/validate_re.rb b/lib/puppet/parser/functions/validate_re.rb
index 583f26a..ca25a70 100644
--- a/lib/puppet/parser/functions/validate_re.rb
+++ b/lib/puppet/parser/functions/validate_re.rb
@@ -1,35 +1,40 @@
 module Puppet::Parser::Functions
-
   newfunction(:validate_re, :doc => <<-'ENDHEREDOC') do |args|
-    Perform simple validation of a string against a regular expression.  The second
-    argument of the function should be a string regular expression (without the //'s)
-    or an array of regular expressions.  If none of the regular expressions in the array
-    match the string passed in, then an exception will be raised.
+    Perform simple validation of a string against one or more regular
+    expressions. The first argument of this function should be a string to
+    test, and the second argument should be a stringified regular expression
+    (without the // delimiters) or an array of regular expressions.  If none
+    of the regular expressions match the string passed in, compilation will
+    abort with a parse error.
 
-    Example:
+    If a third argument is specified, this will be the error message raised and
+    seen by the user.
 
-    These strings validate against the regular expressions
+    The following strings will validate against the regular expressions:
 
         validate_re('one', '^one$')
         validate_re('one', [ '^one', '^two' ])
 
-    These strings do NOT validate
+    The following strings will fail to validate, causing compilation to abort:
 
         validate_re('one', [ '^two', '^three' ])
 
-    Jeff McCune <jeff@puppetlabs.com>
+    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|
+    # We're using a flattened array here because we can't call String#any? in
+    # Ruby 1.9 like we can in Ruby 1.8
+    raise Puppet::ParseError, (msg) unless [args[1]].flatten.any? do |re_str|
       args[0] =~ Regexp.compile(re_str)
     end
 
   end
-
 end