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