Mega-commit: Enter the new object model

Note: only standard Zend objects are working now. This is definitely going to
break custom objects like COM, Java, etc. - this will be fixed later.
Also, this may break other things that access objects' internals directly.

1 files changed, 177 insertions, 0 deletions

diff --git a/Zend/OBJECTS2_HOWTO b/Zend/OBJECTS2_HOWTO
new file mode 100644
index 0000000000..9a0222e313
--- /dev/null
+++ b/Zend/OBJECTS2_HOWTO
@@ -0,0 +1,177 @@
+Creating an object
+------------------
+
+Object can be created in the following ways:
+
+1. As a result of a function call. E.g.:
+
+$foo = create_new_foo("parameter");
+$foo->run();
+
+The function should create a new zval, create new object and get the
+handle for it, set handle and handler table as needed. Note that the
+handle is the only ID of the object, so it should be enough to
+identify it.
+
+2. Overriding create_object handler for class. E.g.:
+
+$foo = new Java("some.Class.here", "parameter");
+$foo->run();
+
+The  create_object handler function should create a new zval, create
+new object and get the handle for it, set handle and handler table as
+needed, and also provide constructor method that would handle
+constructor call. The get_constructor handler table entry should be
+used for that. Do not rely class entry's constructor, unless you refer
+to it from get_constructor handler.
+
+Object maintenance
+------------------
+
+The handlers add_ref and del_ref are called when a new zval referring
+to the object is created. This does not create a new object - both
+zvals still refer to the same object.
+
+clone_obj handler should create a new object, identical to an old one, 
+but being a separate entity.
+
+delete_obj should destroy an object, all references to it become
+invalid.
+
+Object access - read
+--------------------
+
+get_property is used to read object's property. This value is not
+meant to be changed. The handler returns zval * with the value.
+
+Object access - write
+---------------------
+
+write_property is used to directly write object's property by
+name. This handler is not oftenly used by the engine itself, but may
+be used by some internal functions.
+
+get_property_ptr is used to obtain zval ** for future writing to
+it. If your object properties are stored as zval*, return real place
+where the property is stored. If the aren't, the best way is to create 
+proxy object and handle it via get and set methods (see below).
+
+get and set handlers are used when engine needs to access the object
+as a value. E.g., in the following situation:
+
+$foo =& $obj->bar;
+$foo = 1;
+
+if $foo is an object (e.g., proxy object from get_property_ptr) it
+would be accessed using write handler.
+
+Object access - method call
+---------------------------
+
+get_method handler is used to find method description by name. It
+should set right type, function name and parameter mask for the
+method. If the type is ZEND_OVERLOADED_FUNCTION, the method would be
+called via call_method handler, otherwise it would be called with
+standard Zend means.
+
+get_constructor performs the same function as get_method, but for the
+object constructor. 
+
+call_method handler is used to perform method call. Parameters are
+passed like to any other Zend internal function. 
+
+Object - comparison
+-------------------
+
+Objects can be compared via compare_objects handler. This is used with 
+== operation, === compares objects by handles, i.e., return true if
+and only if it's really the same object. Note that objects from
+different object types (i.e., having different handlers) can not be
+compared. 
+
+Objects - reflection
+--------------------
+
+get_class_name is used to retrieve class name of the object. No other
+reflection functions are currently implemented.
+
+Objects - data structures and handlers
+---------------------------------------
+
+The object is represented by the following structure:
+
+struct _zend_object_value {
+	zend_object_handle handle;
+	zend_object_handlers *handlers;
+};
+
+handle is an ID of the object among the objects of the same type (not
+class!). The type of the object and how it behaves is determined by
+the handler table.
+
+typedef struct _zend_object_handlers {
+	zend_object_add_ref_t                    add_ref;
+	zend_object_del_ref_t                    del_ref;
+	zend_object_delete_obj_t                 delete_obj;
+	zend_object_clone_obj_t                  clone_obj;	
+	zend_object_read_property_t              read_property;
+	zend_object_write_property_t             write_property;
+	zend_object_get_property_ptr_t           get_property_ptr;
+	zend_object_get_t                        get;
+	zend_object_set_t                        set;
+	zend_object_has_property_t               has_property;
+	zend_object_unset_property_t             unset_property;
+	zend_object_get_properties_t             get_properties;
+	zend_object_get_method_t                 get_method;
+	zend_object_call_method_t                call_method;
+	zend_object_get_constructor_t            get_constructor;
+	zend_object_get_class_name_t             get_class_name;
+	zend_object_compare_t                    compare_objects;
+} zend_object_handlers;
+
+See zend_object_handlers.h for prototypes. All objects are passed as zval's.
+
+Handlers explained:
+
+add_ref - called when a copy of the object handle is created.
+
+del_ref - called when a copy of the object handle is destroyed.
+
+delete_obj - called when an object needs to be destroyed.
+
+clone_obj - called when a new object identical to an old one should be 
+created (unlike Zend Engine 1, this never happens unless explicitly
+asked for).
+
+read_property - returns zval *, containing the value of the
+property. Is used when value of the property should be retrieved for
+reading.
+
+write_property - assigns value to certain property of the object. 
+
+get_property_ptr - retrieves zval** for the property of the value, to
+be used for read and write. If object properties are not zval's
+natively, this method should create and return proxy object for use
+with get and set methods.
+
+get - retrieves zval* for object contents. To be used mainly with
+proxy objects from get_property_ptr, but also may be used for
+convert_to_* functions.
+
+set - sets value for object contents. To be used mainly with
+proxy objects from get_property_ptr.
+
+has_property - checks if the object has certain property set.
+
+unset_property - removes value for the property of the object
+
+get_method - retrieves description of the method
+
+call_method - calls the method (parameters should be put on stack like 
+for any other PHP internal function).
+
+get_constructor - get description for the object constructor method
+
+get_class_name - get the name of the class the object belongs to
+
+compare_objects - compares if two objects are equal