if (builder.hasSuperClass("haxe.ui.core.Component") == false) {
            return "Must have a superclass of haxe.ui.core.Component";
        }

        if (builder.constructor == null) {
            return "A class building component must have a constructor";
        }

        ModuleMacros.populateClassMap();

        var xml = builder.getClassMetaValue("xml");
        var namedComponents:Map<String, String> = new Map<String, String>();
        var expr = ComponentMacros.buildComponentFromString([], xml, namedComponents);
        var codeBuilder = new CodeBuilder(expr);
        codeBuilder.add(macro
            addComponent(c0)
        );

        var createChildrenFn = builder.findFunction("createChildren");
        if (createChildrenFn == null) {
            createChildrenFn = builder.addFunction("createChildren", macro {
                super.createChildren();
            }, [APrivate, AOverride]);
        }
        createChildrenFn.add(codeBuilder);

        for (id in namedComponents.keys()) {
            var safeId:String = StringUtil.capitalizeHyphens(id);
            var cls:String = namedComponents.get(id);
            builder.addVar(safeId, TypeTools.toComplexType(Context.getType(cls)));
            builder.constructor.add(macro
                $i{safeId} = findComponent($v{id}, $p{cls.split(".")}, true)
            , 1);
        }

        return null;