Filed under "wouldn't it be nice" ;-)

dream.groovy

def matcher = ~/(?<year>\d\d\d\d)-(?<month>\d\d)-(?<day>\d\d)/

switch('2014-10-10') {
    case matcher: { year, month, day ->
        println "On day $day of month $month, in the year $year"
    }
}

We can almost get there, as thanks to Groovy's ignorance of all things private, we can do:

def matcher = ~/(?<year>\d\d\d\d)-(?<month>\d\d)-(?<day>\d\d)/

switch('2014-10-10') {
    case matcher: println matcher.namedGroups()
}

To print out:

[month:2, year:1, day:3]

Or indeed:

import java.util.regex.*

def matcher = ~/(?<year>\d\d\d\d)-(?<month>\d\d)-(?<day>\d\d)/

switch('2014-10-15') {
    case matcher: println matcher.namedGroups()
                                 .collectEntries { k, v -> [k, Matcher.lastMatcher.group(v)] }
                                 .with {
        println "On day $day of month $month, in the year $year"
    }
}

If you like typing ;-)