NYCPHP Meetup

[nycphp-talk] nested objects

Hans Zaunere hans at nyphp.org
Tue Feb 11 09:23:16 EST 2003


Hey Michael,

--- Michael Welsh <welsh_michael at hotmail.com> wrote:
> Can I create an object that, in turn, creates another object within one of 
> its functions?

Yes, although technically these are nested objects.  Nested classes (if I
understand correctly) will only be available starting in PHP 5
(http://www.php.net/ZEND_CHANGES.txt).

> I have a db_class that accepts an SQL statement.  It creates a connection 
> thru ODBC and returns a recordset.  I have a foo_class that (tries to) call
> the db_class to fill itself up.  The main PHP page creates a new foo then 
> does something like new_foo->get_data.

A trivial example perhaps:

class db_class {
   var $SQLStmt = NULL;

   function setSQL( $stmt ) {
      if( is_string($sql) )
         $this->SQLStmt= do_escaping($stmt);
   }

   function runData() {
      if( !$this->SQLStmt)
         return NULL;

      $recordset = do_odbc($this->SQLStmt);
      if( is_array($recordset) )
         return $recordset;

      return NULL;
   }
}

class foo_class {
   var $DB = NULL;

   var $Name = NULL;
   var $PhoneNumber = NULL;
   var $Email = NULL;

   function getData( $id ) {
      if( !is_numeric($id) )
         return FALSE;

      $this->DB = &new db_class;
      $this->DB->setSQL("SELECT name,phone,email FROM table WHERE id='$id'");
      $tmp = $this->DB->runData();
      if( !$tmp ) {
         trigger_error('runData() Failed');
         return FALSE;
      }

      list($this->Name,$this->PhoneNumber,$this->Email) = $tmp;
      return TRUE;
   }
}

$afoo = &new foo_class;
if( $afoo->getData(1234) )
   echo 'Looks Good';
else
   echo 'Looks Bad';


Hopefully that doesn't confuse things, is along the lines of what you're
doing, and would actually work in a real implementation.

> Procedurally, it works.  I did that to test the syntax and the ODBC call.  
> But, when I nest the objects the db_class fails saying Unknown fucntion: 
> odbc_exec.  It *appears* that it does not have a valid conn_id.

Although there's no reason I can think that a PHP-space function would work
procedurally and not within objects, be careful about using constructors. 
Because of the way references work, you can end up with some funny objects.

Hans



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