Extends groovy.time.TimeCategory with the ability to cast Strings into Dates.

EasyDateCategory.groovy

class EasyDateCategory extends groovy.time.TimeCategory {
    static asType(String str, Class clazz) {
        if (clazz == Date) {
            new java.text.SimpleDateFormat('yyyy-MM-dd').parse(str)
        } else {
            str.asType(clazz)
        }
    }
}

use(EasyDateCategory) {
    println(('2014-02-25' as Date) + 3.months)
}