Question

I am building a class that turns a flatfile into a virtual database, I am trying to take the values of an array as the column names instead of indexes when retrieving data like so…

$db = new Database($config, array('first', 'second', 'third', 'fourth'), true);

The array is sent to the constructor in database.php:

public function __construct(Config $config, array $constants = null, $caseInsensitive = false)  {
            $this->_config = $config;
            if(!is_null($constants))
                $this->defineColumns($constants, $caseInsensitive);
            return true;
        } 

Which is passed on to defineColumns():

private function defineColumns($constants, $caseInsensitive) {
            for ($i=0;$i<count($constants);$i++)
                define($constants[$i], $i, $caseInsensitive);   
        }

This works and I can now use first to access column 0, second to access column 1 and so on…

However the define() function seems to make the constants global and accessible from outside the class instance.

I want each set of declared constants to be scoped to the instance alone allowing me to use the same constant again in another instance of the class to access a different column.

Does anyone know a way of doing this?

Answer 1

I’m afraid is not possible if you want to use constants. Constants are global.

By not using constants, you can store that names in a class static member and use them with something like $myinstance->get('third').

protected static $columns = array();

private function defineColumns($constants) {
    for ($i=0;$i<count($constants);$i++)
        self::$columns[$constants[$i]] = $i;    
}

public function get($column) {
    return $IDONTKNOWYOURIMPLEMENTATION[ self::$columns[$column] ];
}