danveloper

datasource.url=jdbc:h2:mem:devDb;MVCC=TRUE;LOCK_TIMEOUT=10000
datasource.username=sa
datasource.pooled=true
datasource.driverClassName=org.h2.Driver
datasource.username=sa
datasource.password=
datasource.dbCreate=create-drop
datasource.url=jdbc:h2:mem:devDb;MVCC=TRUE;LOCK_TIMEOUT=10000

danveloper

configurations.all {
    resolutionStrategy.cacheChangingModulesFor 0, 'seconds'
}

danveloper

def bar(name) {
    "bar: $name"
}
def foo(k, name = bar(k)) {
    "$name"
}

assert foo("ha") == "bar: ha"

danveloper

public interface RulesEngine {}

danveloper

class Student {
    enum DormHall {
        Honors, Preferred, Normal
    }
    def firstName
    def lastName
    def gpa
    
    // We only want dormHall to be assigned when it is deliberate, so throw an exception when
    // it is accidentally assigned outside of our rules engine

danveloper

class RulesEngineFactory<E extends RulesEngine> {
    private final E engine
    public RulesEngineFactory(final Class<E> c) {
        this.engine = (E)c.newInstance()
        this.engine.engine = this.engine
    }
    
    def getObject(final def obj) {
        this.engine.obj = obj
        this.engine

danveloper

class EnrollmentRulesEngine extends RulesEngineSupport<Student> implements RulesEngine {
    def dormHallRule = { obj ->
        if (obj.gpa >= 3.5) {
            obj.@dormHall = Student.DormHall.Honors
        } else if (obj.gpa >= 3.0) {
            obj.@dormHall = Student.DormHall.Preferred
        } else {
            obj.@dormHall = Student.DormHall.Normal
        }
    }

danveloper

class RulesEngineSupport<E> {
    RulesEngine engine
    E obj
    
    // Deduce the rule list for a given RulesEngine instance
    def getRules() {
        def rules = []
        engine.class.declaredFields.each {
            def field = engine."${it.name}"
            if (!it.isSynthetic() && field instanceof Closure && it.name.endsWith("Rule")) {

danveloper

class EnrollmentProcessor {
    static def enrollmentRulesFactory = new RulesEngineFactory<EnrollmentRulesEngine>(EnrollmentRulesEngine)
    def studentService
    
    def annualDormHallAssignment() {
        def students = Student.list(/* do some filtering maybe to make sure they are enrolling for this year,etc. */)
        def errors = []
        students.each { student ->
            try {
                def studentEnrollmentRulesEngine = enrollmentRulesFactory.getObject(student)

danveloper

/**
*
*   Structure:
*    + module: model
*      - class: com.danveloper.model.Student
*
**/
class Student {
    enum DormHall {
        Honors, Preferred, Normal