1Creating an object 2------------------ 3 4Object can be created in the following ways: 5 61. As a result of a function call. E.g.: 7 8$foo = create_new_foo("parameter"); 9$foo->run(); 10 11The function should create a new zval, create new object and get the 12handle for it, set handle and handler table as needed. Note that the 13handle is the only ID of the object, so it should be enough to 14identify it. 15 162. Overriding create_object handler for class. E.g.: 17 18$foo = new Java("some.Class.here", "parameter"); 19$foo->run(); 20 21The create_object handler function should create a new zval, create 22new object and get the handle for it, set handle and handler table as 23needed, and also provide constructor method that would handle 24constructor call. The get_constructor handler table entry should be 25used for that. Do not rely class entry's constructor, unless you refer 26to it from get_constructor handler. 27 28Object maintenance 29------------------ 30 31The handlers add_ref and del_ref are called when a new zval referring 32to the object is created. This does not create a new object - both 33zvals still refer to the same object. 34 35clone_obj handler should create a new object, identical to an old one, 36but being a separate entity. 37 38delete_obj should destroy an object, all references to it become 39invalid. 40 41Object access - read 42-------------------- 43 44read_property is used to read object's property. This value is not 45meant to be changed. The handler returns zval * with the value. 46 47Object access - write 48--------------------- 49 50write_property is used to directly write object's property by 51name. This handler is used to assign property variables or to change them 52in operations like += or ++ (unless get_property_zval_ptr is also set). 53 54get_property_zval_ptr is used to obtain pointer to modifiable zval for 55operations like += or ++. This should be used only if your object model 56stores properties as real zval's that can be modified from outside. 57Otherwise this handler should be NULL and the engine will use 58read_property and write_property instead. 59 60get_property_ptr is used to obtain zval ** for future writing to 61it. If your object properties are stored as zval*, return real place 62where the property is stored. If the aren't, the best way is to create 63proxy object and handle it via get and set methods (see below). 64This method is meant to be used for send-by-reference and assign-by-reference 65use of object properties. If you don;t want to implement property 66referencing for your objects, you can set this handler to NULL. 67 68get and set handlers are used when engine needs to access the object 69as a value. E.g., in the following situation: 70 71$foo =& $obj->bar; 72$foo = 1; 73 74if $foo is an object (e.g., proxy object from get_property_ptr) it 75would be accessed using write handler. 76 77Object access - method call 78--------------------------- 79 80get_method handler is used to find method description by name. It 81should set right type, function name and parameter mask for the 82method. If the type is ZEND_OVERLOADED_FUNCTION, the method would be 83called via call_method handler, otherwise it would be called with 84standard Zend means. 85 86get_constructor performs the same function as get_method, but for the 87object constructor. 88 89call_method handler is used to perform method call. Parameters are 90passed like to any other Zend internal function. 91 92Object - comparison 93------------------- 94 95Objects can be compared via compare_objects handler. This is used with 96== operation, === compares objects by handles, i.e., return true if 97and only if it's really the same object. Note that objects from 98different object types (i.e., having different handlers) can not be 99compared. 100 101Objects - reflection 102-------------------- 103 104get_class_name is used to retrieve class name of the object. 105get_class_entry returns class entry (zend_class_entry) for the object, 106in case there exists PHP class for it. 107No other reflection functions are currently implemented. 108 109Objects - data structures and handlers 110--------------------------------------- 111 112The object is represented by the following structure: 113 114struct _zend_object_value { 115 zend_object_handle handle; 116 zend_object_handlers *handlers; 117}; 118 119handle is an ID of the object among the objects of the same type (not 120class!). The type of the object and how it behaves is determined by 121the handler table. 122 123typedef struct _zend_object_handlers { 124 zend_object_add_ref_t add_ref; 125 zend_object_del_ref_t del_ref; 126 zend_object_delete_obj_t delete_obj; 127 zend_object_clone_obj_t clone_obj; 128 zend_object_read_property_t read_property; 129 zend_object_write_property_t write_property; 130 zend_object_get_property_ptr_t get_property_ptr; 131 zend_object_get_property_zval_ptr_t get_property_zval_ptr; 132 zend_object_get_t get; 133 zend_object_set_t set; 134 zend_object_has_property_t has_property; 135 zend_object_unset_property_t unset_property; 136 zend_object_get_properties_t get_properties; 137 zend_object_get_method_t get_method; 138 zend_object_call_method_t call_method; 139 zend_object_get_constructor_t get_constructor; 140 zend_object_get_class_entry_t get_class_entry; 141 zend_object_get_class_name_t get_class_name; 142 zend_object_compare_t compare_objects; 143} zend_object_handlers; 144 145See zend_object_handlers.h for prototypes. All objects are passed as zval's. 146 147Handlers explained: 148 149add_ref - called when a copy of the object handle is created. 150 151del_ref - called when a copy of the object handle is destroyed. 152 153delete_obj - called when an object needs to be destroyed. 154 155clone_obj - called when a new object identical to an old one should be 156created (unlike Zend Engine 1, this never happens unless explicitly 157asked for). 158 159read_property - returns zval *, containing the value of the 160property. Is used when value of the property should be retrieved for 161reading. 162 163write_property - assigns value to certain property of the object. 164 165get_property_zval_ptr - retrieves zval** for being directly modified by 166the engine. If your properties are not zval's, don't define it. 167 168get_property_ptr - retrieves zval** for the property of the value, to 169be used for read and write. If object properties are not zval's 170natively, this method should create and return proxy object for use 171with get and set methods. 172 173get - retrieves zval* for object contents. To be used mainly with 174proxy objects from get_property_ptr, but also may be used for 175convert_to_* functions. 176 177set - sets value for object contents. To be used mainly with 178proxy objects from get_property_ptr. 179 180has_property - checks if the object has certain property set. 181 182unset_property - removes value for the property of the object 183 184get_method - retrieves description of the method 185 186call_method - calls the method (parameters should be put on stack like 187for any other PHP internal function). 188 189get_constructor - get description for the object constructor method 190 191get_class_entry - should return the class entry for the object 192 193get_class_name - get the name of the class the object belongs to 194 195compare_objects - compares if two objects are equal 196
