Late Static Binding in PHP < 5.3

Use case

Even though PHP 5.3 is already out since more than one and a half year, a lot of web-hosters still don’t provide this version. In one of my projects I had to deal with the webhoster all-inkl. The project is written in PHP 5.3, but all-inkl supports PHP 5.2 only. Indeed they offer the possibility to use CGI version for PHP >5.2, but that doesn’t make me happy. So I tried to downgrade the project as successfull as possible.. But when it comes to 5.3′s Late Static Binding I faced problems to rebuild this functionality within 5.2. But after hours of searching the web and testing each approaches, I wrote my own hunky-dory function to fake LSB.

Solution

if( !function_exists( 'get_called_class' ) ) {
  class class_tools {        

    static $i = 0;        
    static $fl = null;

    static function get_called_class() {            
      $bt = debug_backtrace();
      if( self::$fl == $bt[2]['file'].$bt[2]['line'] ) {
        self::$i++;            
      } else {                
        self::$i = 0;                
        self::$fl = $bt[2]['file'].$bt[2]['line'];            
      }

      $lines = file($bt[2]['file']);
      preg_match_all(
        '/([a-zA-Z0-9\_]+)::'.$bt[2]['function'].'/',                
        $lines[$bt[2]['line']-1],                
        $matches            
      );             
      return $matches[1][0];        
    }    
  }

  function get_called_class() {        
    return class_tools::get_called_class();    
  }
}

Conclusion

This faked LSB gets only included if no native support for get_called_class exists (PHP <5.3). Otherwise the parser won’t recognize this code. Even though a lot of code examples don’t deal with the second index of the debug_backtrace-result ($bt[2]), for me it was/is the only way to make that LSB work correctly.