I have a C++ object, Graph, which contains a property named cat of type Category. I'm exposing the Graph object to PHP in an extension I'm writing in C++.

As long as the Graph's methods return primitives like boolean or long, I can use the Zend RETURN_*() macros (e.g. RETURN_TRUE(); or RETURN_LONG(123);. But how can I make

Graph->getCategory();

return a Category object for the PHP code to manipulate?

I'm following the tutorial over at http://devzone.zend.com/article/4486, and here's the Graph code I have so far:

#include "php_getgraph.h"

zend_object_handlers graph_object_handlers;
struct graph_object {
 zend_object std;
 Graph *graph;
};

zend_class_entry *graph_ce;
#define PHP_CLASSNAME "WFGraph"

ZEND_BEGIN_ARG_INFO_EX(php_graph_one_arg, 0, 0, 1)
ZEND_END_ARG_INFO()

ZEND_BEGIN_ARG_INFO_EX(php_graph_two_args, 0, 0, 2)
ZEND_END_ARG_INFO()


void graph_free_storage(void *object TSRMLS_DC) 
{
 graph_object *obj = (graph_object*)object;
 delete obj->graph;

 zend_hash_destroy(obj->std.properties);
 FREE_HASHTABLE(obj->std.properties);

 efree(obj);
}

zend_object_value graph_create_handler(zend_class_entry *type TSRMLS_DC) 
{
 zval *tmp;
 zend_object_value retval;

 graph_object *obj = (graph_object*)emalloc(sizeof(graph_object));
 memset(obj, 0, sizeof(graph_object));
 obj->std.ce = type;

 ALLOC_HASHTABLE(obj->std.properties);
 zend_hash_init(obj->std.properties, 0, NULL, ZVAL_PTR_DTOR, 0);
 zend_hash_copy(obj->std.properties, &type->default_properties, (copy_ctor_func_t)zval_add_ref, (void*)&tmp, sizeof(zval*));

 retval.handle = zend_objects_store_put(obj, NULL, graph_free_storage, NULL TSRMLS_CC);
 retval.handlers = &graph_object_handlers;

 return retval;
}

PHP_METHOD(Graph, __construct)
{
 char *perspectives;
 int perspectives_len;
 Graph *graph = NULL;
 zval *object = getThis();

 if(zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", &perspectives, &perspectives_len) == FAILURE) { 
  RETURN_NULL();
 }

 graph = new Graph(perspectives);
 graph_object *obj = (graph_object*)zend_object_store_get_object(object TSRMLS_CC);
 obj->graph = graph;
}
PHP_METHOD(Graph, hasCategory)
{
 long perspectiveId;

 Graph *graph;
 graph_object *obj = (graph_object*)zend_object_store_get_object(getThis() TSRMLS_CC);
 graph = obj->graph;

 if (graph == NULL) {
  RETURN_NULL();
 }

 if(zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "l", &perspectiveId) == FAILURE) { 
  RETURN_NULL();
 }

 RETURN_BOOL(graph->hasCategory(perspectiveId));
}
PHP_METHOD(Graph, getCategory)
{
 // what to do here?
 RETURN_TRUE;
}
function_entry php_getgraph_functions[] = {
 PHP_ME(Graph,__construct,NULL,ZEND_ACC_PUBLIC|ZEND_ACC_CTOR)

 PHP_ME(Graph,hasCategory,php_graph_one_arg,ZEND_ACC_PUBLIC) 
 PHP_ME(Graph,getCategory,php_graph_one_arg,ZEND_ACC_PUBLIC) 
 { NULL, NULL, NULL }
};

PHP_MINIT_FUNCTION(getgraph)
{
 zend_class_entry ce;
 INIT_CLASS_ENTRY(ce, PHP_CLASSNAME, php_getgraph_functions);
 graph_ce = zend_register_internal_class(&ce TSRMLS_CC);
 graph_ce->create_object = graph_create_handler;
 memcpy(&graph_object_handlers, zend_get_std_object_handlers(), sizeof(zend_object_handlers));
 graph_object_handlers.clone_obj = NULL;
 return SUCCESS;
}

zend_module_entry getgraph_module_entry = {
#if ZEND_MODULE_API_NO >= 20010901
 STANDARD_MODULE_HEADER,
#endif
 PHP_GETGRAPH_EXTNAME,
 NULL,                   /* Functions */
 PHP_MINIT(getgraph),
 NULL,                   /* MSHUTDOWN */
 NULL,                   /* RINIT */
 NULL,                   /* RSHUTDOWN */
 NULL,                   /* MINFO */
#if ZEND_MODULE_API_NO >= 20010901
 PHP_GETGRAPH_EXTVER,
#endif
 STANDARD_MODULE_PROPERTIES
};

#ifdef COMPILE_DL_GETGRAPH
 extern "C" {
  ZEND_GET_MODULE(getgraph)
 }
#endif