Groovy Goodness: Canonical Annotation to Create Mutable Class

With Groovy 1.8 we get a lot of AST transformations. We can combine @ToString, @EqualsAndHashCode and @TupleConstructor with the @Canonical annotation. This annotation will do all the transformations at once. If we want to customize one of the AST transformations, we add the annotation with configuration parameters extra after @Canonical.

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import groovy.transform.*   @Canonical class Building {     String name     int floors     boolean officeSpace }   // Constructors are added. def officeSpace = new Building('Initech office', 1, true)   // toString() added. assert officeSpace.toString() == 'Building(Initech office, 1, true)'   // Default values are used if constructor // arguments are not assigned. def theOffice = new Building('Wernham Hogg Paper Company') assert theOffice.floors == 0 theOffice.officeSpace = true   def anotherOfficeSpace = new Building(name: 'Initech office', floors: 1, officeSpace: true)   // equals() method is added. assert anotherOfficeSpace == officeSpace   // equals() and hashCode() are added, so duplicate is not in Set. def offices = [officeSpace, anotherOfficeSpace, theOffice] as Set  assert offices.size() == 2 assert offices.name.join(',') == 'Initech office,Wernham Hogg Paper Company'   @Canonical @ToString(excludes='age')  // Customize one of the transformations. class Person {     String name     int age }   def mrhaki = new Person('mrhaki', 37) assert mrhaki.toString() == 'Person(mrhaki)'