OOP...what's the point?

epp_b

What, exactly, is the objective (pun intended 😃) of object-oriented programming in PHP?

As far as I can tell, they serve a similar purpose as a modular, user-defined function. What benefits are there of OOP?

drawmack

it's a different way of looking at programming.

Procedural based programs (those that rely on modular udfs) look at the program they way a mechanic looks at a tool box. They say I have sand paper, saws, screw drivers, hammers and wrenches. Then everytime something comes through they look at all their tools and see which ones fit.

Object oriented programmers look at things the other way around. They say I have wood. I can hammer, saw, sand, drill, stain and nail wood. Now everytime the programmer is given wood they already know how to deal with it.

It's a means of encapsulation and modularity.

Tristan_Wells

I for one use OOP to save development time. Building my vars and objects into classes allows me to recycle alot of code eassier than in procedural coding. Which means I don't have to code the same stuff over and over again.

OOP also allows you to make custom functions with the same name that do different things. For instance,
I can have 2 auth classes. One for sessions and one for cookies. I can have $cookies->set and $session->set. Whereas If I used procedural code I would have to do something like cookie_set() and session_set. Recreating any function/class for that purpose would be kind of silly though. Im just trying to provide an example.

It really makes no difference how you use PHP. It all depends on what you feel comfortable using.

drawmack

To extrapolate on what tristan is saying.

I have a guestbook that I wrote and depending on the class I hook it into it can store info in text files, xml, mysql or postgre. No coding needed. I've set it up so that it uses a global constant to know which one to use so I just make a change to a value in a config file and it'll work.

Tristan_Wells

Also OOP is alot less chaotic. I was actually getting grey hair and loosing sleep when coding in procedural. Then my good freind who is also a PHP developer converted me to OOp. Only one grey hair since.

epp_b

I understand the concept of OOP being built to modularize programming, but do functions not do the same (or similar) thing?

eg.:

function myFunc($myPassedVar) {
   if ($myPassedVar > 5) {
      return "more than five";
   }
   else {
     return "less than five";
   }
}

echo myFunc(4);

class myClass {
   var $myVar;

   function myFunc($myPassedVar) {
      if ($myPassedVar> 5) {
        return "more than five";
      }
      else {
        return "less than five";
      }
   }
}

$myTestClassVar = new myClass;
echo $myTestClassVar->myFunc(4);

Obviously, both these chunks of code will return the same thing. I know that OOP can do a lot more than this, being a minimal example, but what advantages does it have over modular user-defined functions?

Drakla

Ok - Say you're doing some MySQL and you have to keep track of a database connection, result resource and all that gunk, well you can encapsulate all of those inside an object and just use things like

$db=&new MySQLThing(); //automatically connected to the DB for you with default settings

$db->query("Use mydb");
$db->query($myquery);
$db->fetch_row();

There's no mukking about with all those variables as they're in the database class. Also with MySQL if you create a new connection with the same details as before, unless you specifically ask it not to it'll return the same resource ID, so if you seemingly open two connections in the same script, then close one the other gets closed as well. I write functions to populate dropdowns or whatever from a db and then close them at the end of the function and still get away with it with my slapdash horror of a mysql class that uses a sort of reference counting thing:

class MySQLThing
	{
		var $dbh, $res;
		var $dbCons;	//this will be a simulated static.

	function MySQLThing($user="", $pass="",$host="")
	{
		static $dbCons=array();
		$this->dbCons=&$dbCons;	//this is how the pretend static happens

		$this->connect($host,$user,$pass)
		OR $this->death("Couldn't Connect to MySQL Database:");			
	}

	function connect($host="",$user="",$pass="")
	{
		if($this->dbh) $this->close();
		$res=$this->dbh=mysql_connect($host, $user, $pass);
        @$this->dbCons["$this->dbh"]++;
		/*echo "This Con: $this->dbh<br>";		print_r($this->dbCons);	echo "<br>";	//*/
		return $res;
	}

	function close()
	{
		if ( isset( $this->dbCons["$this->dbh"] ) )
		{
			$refCount=--$this->dbCons["$this->dbh"];
			if( $refCount <= 0)
			{//	echo "CLOSING REF COUNT ZERO<br>";
				return mysql_close($this->dbh);
			}
			//else echo "NOT REALLY CLOSING REF COUNT: $refCount<br>";
		}
		else return 0;
	}

The commented out bits are just my debugging cack, ignore that. Anyway objects save a hell of a lot of headaches.

epp_b

Doh...hit that button by mistake -- sorry for the partial double-post. OK, here I go again:

How different is it to use a function for this example?

function doMySQL_Login() { 
   // access global variables set in a configuration script
   global $MySQL_Server, $MySQL_Username, $MySQL_Password, $MySQL_Database;

   // connect to mysql using those variables as credentials
   mysql_connect($MySQL_Server, $MySQL_Username, $MySQL_Password);
   mysql_select_db($MySQL_Database)
}

Now, whenever I need to connect to the database, It's as simple as typing

doMySQL_Login();

And it would be very simple to modify the function slightly to use parameters as credentials instead of global variables. How does OOP offer any advantage over this?

(BTW, I'm not challenging anyone or trying to say "one way is better than the other", I'm just trying to understand the concepts and advantages of OOP over modularization with user functions)