Hi Boris, On Tue, 2007-07-10 at 15:38 +0200, Boris wrote: > Hi there, > > I'm trying to create an object-oriented PHP 5 extension. As I don't know > any step-by-step tutorial which would explain everything in detail I'm > trying to understand various sources and documents I happen to run into. > I'd appreciate if anyone could comment on what I currently think the > typical steps look like (the more comments the better as it's a rather > random learning process):
Well there's Sara's book (SBN-10: 067232704X or ISBN-13: 978-0672327049) and there are Marcus "Code Camp" slides (while slides without the talk don't work the same) which show all the things step by step. > * Before a class can be used it must be registered with > zend_register_internal_class(). The returned pointer is typically saved in > a global zend_class_entry* (why I don't know - do you need the pointer > somewhere later?). Yes, you need the ce everywhere, where you want to reference that class (checking whether an object passed to to you is of the correct type, checking properties, etc.) > * As you need to register a class before you can use it you must call the > code somewhere - a good place is the module startup function. It is the best place. > * In order to call zend_register_internal_class() you need another another > zend_class_entry first. It can be initialized with INIT_CLASS_ENTRY which > sets the class name and assigns the function table (which contains member > functions declared with PHP_ME). Right, first setup everything on your ce then give it to the engine which makes a copy for further use. > * Classes are instantiated by calling the function assigned to > zend_class_entry::create_object. Thus apart from the initializiation with > INIT_CLASS_ENTRY zend_class_entry::create_object must be set in the module > startup function. An class might work without your own create_object handler, but usually you want to store additional data (like pointers to some complex data structure) inside your object so you have to allocate and initilise that. > * In the create_object function a zend_object is created and initialized > (with zend_object_std_init). Furthermore the default_properties of the > class are copied to the properties of the zend_object (with > zend_hash_copy). Default properties need to be added to zend_class_entry* > after the class is registered in the module startup function (with one of > the many add_property_... functions). yes > * As the create_object function does not return the newly created > zend_object directly it must be stored in a zend_object_handle together > with function pointers to a destructor, free storage function and storage > clone function (is this a copy constructor if you use C++ terminology?). > The function zend_objects_store_put() can be used to do all of this. Objects are registered in the object storage, where they live and are referenced by zvals (php variables) > * The zend_object_handle returned by the create_object function needs also > a pointer to zend_object_handlers. This is a hash table which contains > various object handlers - among others functions to read/write properties. > The object handlers object is typically created and initialized in the > module startup function (as it is the same for all objects of the same > class). Is there any overview what these object handlers are used for and > when exactly you should define your own? I especially wonder what the > read/write property handlers are good for as you define properties in the > class? They don't seem to be unimportant though as I've seen dozens of > them in the DOM extension for example. There's a file Zend/OBJECTS2_HOWTO or similar which should list all handlers. read/write property handlers act similar to __get/__set in userland, you can overwrite them if you don't want to use "regular" properties but directly modify stuff in your internal structures or offer read-only properties. johannes -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: http://www.php.net/unsub.php
