Groovy for Domain-specific Languages - Second Edition

Chapter 7

[ 181 ]

when:

BusinessService.isRemoteServiceLive()

then:

thrown NullPointerException

when:

BusinessService.metaClass.static.isRemoteServiceLive =

{ true }

def live = BusinessService.isRemoteServiceLive()

then:

notThrown NullPointerException

live == true

Dynamic method naming

We can use GStrings to name methods as we add or override them in a class. This
means that we can dynamically generate method names on the fly. In the following
example, we iterate all of the properties in the Customer class. We can exclude the
class and metaClass properties with the find operator it =~ /lass/ so that we
just add methods for the properties that we want:

class Customer {

int id

String firstName

String surname

String street

String city

}

given:

def c = new Customer()

c.properties.keySet().findAll { !(it =~ /lass/)}.each {

Customer.metaClass."idFor${it.capitalize()}" = { ->

delegate."$it".toString().toLowerCase().tr(' ', '_')

}

}

when:

def cust = new Customer(firstName:"Fred",

surname:"Flintstone",

street:"Rock Road",

city:"Bedrock")