Variable variable $$var in a class

PHP
1

I’m attempting to create a class for use with multiple databases (don’t tell me there are already classes that do this, I have an assignment to create my own).

I’m attempting to capitalize on this functionality:


<?php

  function test($value)
  {
    print $value;
  }
  
  $testF = "test";
  
  $testF('Newt');

?>

But am having some difficulty figuring out the syntax to use in a class with a class wide variable. Here is the code:


<?php

  $testLayer = new Test('root', 'a', 'test', 'mysql');
  $sql       = 'SELECT * FROM tblmedia';
  $testLayer->query($sql);

  class Test
  {
    private $dbType     = '';
    private $connection = '';
    private $mysql      = array('query'    => 'mysql_query',
                                'getAssoc' => 'mysql_fetch_assoc',
                                'numRows'  => 'mysql_num_rows');
    private $postgreSQL = array('query'    => 'pg_query',
                                'getAssoc' => 'pg_fetch_assoc',
                                'numRows'  => 'pg_num_rows');
                                
    public function __construct($un, $pw, $db, $dbType = 'mysql', $host = 'localhost')
    {
      $this->dbType = $dbType;
      
      switch($this->dbType):
        case 'mysql':
          $this->connection = mysql_connect($host, $un, $pw);
          mysql_select_db($db, $this->connection);
          break;
          
        case 'postgreSQL':
          $conString = 'host='.$host.' user='.$un.' password='.$pw.' dbname='.$db;
          $this->connection = pg_connect($conString);
          break;
      endswitch;
    }
    
    public function query($sql)
    {
      $result = $this->{$$this->dbType}['query']($sql); // [COLOR=Red]<------- here is the issue[/COLOR]
      $this->fb($$this->dbType['getAssoc']($result), 'Results');
    }
    
    ///////////////////////////////////////////////////////
    //  This method returns array and variable values
    //  to the screen
    //
    //  View source to see the results
    //
    //  Used internally for debugging
    //
    private function fb($value, $text = 'Feedback')
    {
      print '<!-- '.$text.':
';
      print_r($value);
      print ' -->

';
      return;
    }      
  }

?>

I’m attempting to execute a function listed in the associative array utilizing the $$var syntax, but I’m unclear on how this is to be done on a class wide variable. This does not work, $this->{$$this->dbType}‘query’

Anyone know how/if this can be done?

Thanks in advance!

2

Looks like this is the syntax:


    public function query($sql)
    {
      $result = $this->{$this->dbType}['query']($sql);
      $this->fb($this->{$this->dbType}['getAssoc']($result), 'Results');
    }