looks like typo here. I prefer if you use for option names variables, constants anything.
Second note is design one that leads to this. You should have it tight together. so for me better structure is map of map like this:
```
const string OPTION_VALIDATOR = "option validator";
const string OPTION_SETTER = "option setter";
const string FAIL_MESSAGE = "fail message";
map<string,map<string,any> > options = $[
  "hostname": $[ OPTION_VALIDATOR: Hostname::Check,
                         OPTION_SETTER: SetHostname,
                         FAIL_MESSAGE: _( "InvalidHostname. ") + Hostname::ValidHost()
                      ]
....
];
```
this way you don't need constant for options as it is not repeated. You also have it in one place and it is easier to extend it, as you know that you must add it to this one map.