def output = { it ->
    println it
}

class StringHelper {}

class DomainService {}

ClassLoader parent = this.getClass().getClassLoader()
def classes = parent.getLoadedClasses()
def helpers = classes.findAll { it.name.endsWith('Helper') }
def services = classes.findAll { it.name.endsWith('Service') }

helpers.each { helper ->
    helper.metaClass."handleSomething" = { println "handleSomething" }
}

services.each { service ->
    service.metaClass."save" = { println "save" }
    service.metaClass."load" = { println "load" }
    service.metaClass."delete" = { println "delete" }
}

def stringHelper = new StringHelper()
stringHelper.handleSomething()

def domainService = new DomainService()
domainService.save()
domainService.load()
domainService.delete()