Synthetic class in Groovy using compiler API.

SyntheticClassTest.groovy

// Fixed synthetic class snippet originally from <anonimista@outlook.com>.

import groovyjarjarasm.asm.Opcodes
import org.codehaus.groovy.ast.*
import org.codehaus.groovy.ast.expr.*
import org.codehaus.groovy.control.*
import org.codehaus.groovy.tools.GroovyClass

CompilationUnit compilationUnit = new CompilationUnit()

def className = 'Position'

// This gets an NPE...
//ClassNode classNode = ClassHelper.make(className)
//classNode.superClass = ClassHelper.OBJECT_TYPE
//classNode.modifiers = Opcodes.ACC_PUBLIC

ClassNode classNode = new ClassNode(className, Opcodes.ACC_PUBLIC, ClassHelper.OBJECT_TYPE)

FieldNode xFieldNode = new FieldNode(
        'x', FieldNode.ACC_PUBLIC,
        ClassHelper.Integer_TYPE, classNode,
        new ConstantExpression(0))

FieldNode yFieldNode = new FieldNode(
        'y', FieldNode.ACC_PUBLIC,
        ClassHelper.Integer_TYPE, classNode,
        new ConstantExpression(0))

classNode.addField(xFieldNode)
classNode.addField(yFieldNode)

compilationUnit.addClassNode(classNode)

compilationUnit.compile(Phases.CLASS_GENERATION)

def classes = compilationUnit.getClasses()
println classes

// Really should load all the classes and find the one we want by name.
// This approach based on the implementation of o.c.g.transform.stc.StaticTypeCheckingSupport.evaluateExpression(...).
Class aClass = compilationUnit.getClassLoader().defineClass(className, classes.head().getBytes())
println aClass

def instance = aClass.newInstance()
instance.x = 1
instance.y = -4

// We've got a POJO rather than POGO because we've bypassed the compiler logic that adds the Groovy magic.
// That'll be true even if we use ClassHelper.GROOVY_OBJECT_SUPPORT_TYPE for the ClassNode.
// So synthesizing a POGO would take more investigation.

println instance
println instance.getProperties()
println ([x:instance.x, y:instance.y])