PojoBuilder New Feature Proposal

Added an AST transformation @PojoBuilder that creates for given provided Pojo builder class "with" methods that allow to set values on a Pojo together with the "build" method that allows to instantiate it.

Example:

POJO - Person

          
class Person {
               String firstName
               String surName
           }

PersonBuilder

          @PojoBuilder(forClass = Person)
          class PersonBuilder {

          }

Building

       def person = personBuilder.withFirstName("Robert").withSurName("Lewandowski").build()

Verification

       assert person.firstName == "Robert"
       assert person.surName == "Lewandowski"

Also added building with validation closure:

try {
            def person = personBuilder.withFirstName("Robert").build {
                if (it.surName == null ){
                    throw new IllegalStateException()
                }
            }
            fail("should fail due to validation closure")
        } catch(Exception exception ) {

        }

Possible extensions:

• Not only for POJOs - for other classes too (right now the object is constructed by picking the default constructor - it can be changed by picking the largest constructor and basing on the types, names etc. create proper "with" methods
• A "withCustomLogic" method that takes a closure as argument and performs custom logic on object to be built
• ImmutableBuilder that at each "with" method creates a new builder instead of setting values on itself

Pull request: https://github.com/groovy/groovy-core/pull/341