RE: [PHP] PHP5 objects access/instantiation model (correction)

Yeah. I've been working on re-writing it using bits from everyone !! It's a good learning process to find out how PHP handles OOP. I thoroughly recommend it, it's the only way to learn. Some things just can't be learnt from the manual! Cheers All. -----Original Message----- From: Richard Lynch [mailto:ceo@l-i-e.com] Sent: 11 July 2007 21:29 To: Steve Perkins Cc: php-general@lists.php.net Subject: Re: [PHP] PHP5 objects access/instantiation model (correction) You probably ought to have: class mysql_driver extends generic_driver { } Seems like that would be the most reasonable OOP model, imho. That said, I suspect that if you do something like: $driver = $this->driver; You then may be able to access the driver-specific data using $driver->propl; etc. On Wed, July 11, 2007 10:46 am, Steve Perkins wrote: > OK, so that came out fairly illegible. Try again: > > Hi, new to PHP5 (and the forums evidently !) and I have a question > about the object model. > > I want to be able to create a class which is allows abstraction from > specifics. So for one example, imagine a generic database connection > wrapper which can have multiple drivers depending on the database > used. Some of the functionality is generic, some is database specific > (mysql_ , odbc_). > So: > > Class MySQL_driver { > public prop1 ; > public connect() { > echo "Foo"; > } > public runquery() { > echo "Foo"; > } > ... > } > > Class ODBC_driver { > public prop1 ; > public connect() { > echo "Foo"; > } > public runquery() { > echo "Foo"; > } > ... > } > > Class generic { > public $driver = null ; > function __construct($connection_type) { > if $this->connection_type = "MySQL" { > $this->driver = new MySQL_Driver ; > } else { > $this->driver = new ODBC_Driver ; > } > } > > // Using the non-generic connect() from the selected driver > > function authenticate { > $this->driver->prop1 = "fooey" > > // These references work fine from within > // the generic class > > echo $this->driver->prop1 ; > echo $this->driver->function1 ; > } > > // Report non-generic errors from the selected driver > > function errors { > } > function debug { > } > > ... > > } > > $gen = new generic("MySQL") ; > > // Instantiate the generic database object, which // determines its > own driver > > $gen->driver->prop1 = "fooey" > > // but they fail from here > > echo $gen->driver->prop1 ; > echo $gen->driver->function1 ; > > // this works ok though, so everything is created // correctly > > $gen->authenticate() ; > > > So I want to access generic functions as $generic->authenticate(), and > database specific functions $generic->driver->runquery. This allows > the top level code to be able to be completely generic and not know > anything about the underlying database. > > But I can't ! I can't find a way of accessing the encapsulated object > (driver) from the instantiator of generic. Is it possible ? > > I guess there are lots of "workaround" ways. I could write lots of > "middleman" code in generic and use things like __set and __get etc > but its lots of extra overhead. I also know I could use extends but > that makes the code the wrong way around (MySQL_Driver would have to > extend generic), hence the top-level application would have to include > code to determine which driver to create rather than the db object > determining its own connection driver to use. This is true also for > just lumping everything in a single class per db type. > > Surely it must be possible ? Or am I missing something ? > > I also don't really get the idea of interface and abstract classes ? > They > don't seem to be any practical use ? Maybe that's me ? Anyway, not > really relevant to this post ... > > Please, please can someone help !! > > Thanks > > -- > PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: > http://www.php.net/unsub.php > > -- > PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: > http://www.php.net/unsub.php > > -- Some people have a "gift" link here. Know what I want? I want you to buy a CD from some indie artist. http://cdbaby.com/browse/from/lynch Yeah, I get a buck. So? -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php