Trying code from SO thread: http://stackoverflow.com/questions/11369511/why-does-groovy-think-im-passing-an-instance-of-the-class-from-a-static-method#comment14982771_11369511

gistfile1.txt

$ groovy -version
Groovy Version: 1.8.6 JVM: 1.6.0_33 Vendor: Apple Inc. OS: Mac OS X

$ ls
CharacterMap.groovy	bar.txt

$ groovy -Dlocation=bar.txt CharacterMap.groovy foo
Jul 10, 2012 1:15:31 AM java.lang.Class constructor
WARNING: Server configuration groovy file not configured with system property location
foo

$ cat CharacterMap.groovy 
import static java.util.logging.Logger.*
import static java.util.logging.Level.*

class CharacterMap {
    public static final String CHARACTER_CONFIGURATION = 'location'
    static Map<String,String> characterMap = null
    public static String ASCIIize(String input)
    {
        if (!characterMap)
        {
            def property = System.getProperty( CHARACTER_CONFIGURATION )
            ConfigObject config = null
            if( property ) {
                ConfigSlurper cs = new ConfigSlurper()
                File file = new File( property )
                URL location = file.toURL()
                config = cs.parse(location)
            }
            if (config)
            {
                characterMap = config.characters
            }
            else
            {
                getAnonymousLogger().logp WARNING, getClass().name, 'constructor',
                        "Server configuration groovy file not configured with system property ${CHARACTER_CONFIGURATION}"
                return input
            }
        }
        for (String key: characterMap.keySet())
        {
            if (input.contains(key))
            {
                input = input.replace(key, characterMap.get(key))
            }
        }
        return input
    }

    public static void main(String[] args)
    {
        print ASCIIize(args[0])
    }
}
$