dynamic class structures

[GreenDepth]

i have a thoery that will allow classes to be dynamic in the sense of libraries that are loaded:

have one class as a 'parent' class:

main.class.php:

<?php

   class Open 
  {
        /* includes basic mysql functions.... */

   function Open($lib=false)
   {
     if($lib)
     {
       include("lib." . $lib . ".php");
       return new $lib;
     }
   }

   /* of course, more error checking would occur.... */
  }
?>

and a library would look like this:

lib.site.php:

<?php
    include("main.class.php");

   class site extends Open
   {
      function test()
      {
        echo "this is the library";
      }
   }
?>

in case, this will work:

test.php:

<?php
    include("main.class.php");

$obj = new Open("site");
/* $obj should now be a ref to site... */

$obj->test();
?>

Does anyone agree on this bit of logic of mine?

[poseidix]

I don't 🙂

Something like this is possible in PHP, but I don't think doing it this way is a good practice.

What you in fact are doing is dynamically creating an instance of a class based on a sort of type identifer (eg. "site"). There is a design pattern called "Factory Method" that is about this technique.

Try something like this:

class ObjectFactory
{
 function &createNew($type)
 {
  include("lib." . $type . ".php");
  return new $type;
 }
}

// Test.php
$site =& ObjectFactory::create('site');

Do a Search on Google if you want more information on this pattern.

[GreenDepth]

hmm, thanks, and I will check google on the subject