This strategy is used with the Builder AST transform to create a builder helper class for the fluent and type-safe creation of instances of a specified class. It is modelled roughly on the design outlined here: http://michid.wordpress.com/2008/08/13/type-safe-builder-pattern-in-java/ You define classes which use the type-safe initializer pattern as follows:
import groovy.transform.builder.* import groovy.transform.*While it isn't required to do so, the benefit of this builder strategy comes in conjunction with static type-checking or static compilation. Typical usage is as follows:@ToString@Builder(builderStrategy=InitializerStrategy) class Person { String firstName String lastName int age }
@CompileStatic
def main() {
println new Person(Person.createInitializer().firstName("John").lastName("Smith").age(21))
}
which prints:
Person(John, Smith, 21)If you don't initialise some of the properties, your code won't compile, e.g. if the method body above was changed to this:
println new Person(Person.createInitializer().firstName("John").lastName("Smith"))
then the following compile-time error would result: