Method not receiving attributes from shortcode call, general OOP problems

First, you have to initiate the class, something like:

add_action( 'init', function() {

     $CsvImporter = new CsvImporter;

} );

Also, you are using extract() wrong; extract() won’t build $attributes as an array. Anyway, extract() is not recommended any more and you should avoid using it. Also, note taht if ($attributes['mods']) should be if ($attributes['type'] == 'mods') as mods is not a valid index in $attributes array but the value of type index. Additionally you need to return a value int he shortcode callback.

I’ve tested this shortcode [priceguide file="test.csv" type="mods"] and it is working with the code bellow (note also that I’ve change ’ character in the shortcode, not sure if ’ is a valid value delimiter).

add_action( 'init', function() {

     $CsvImporter = new CsvImporter;

} );

class CsvImporter {   
    private $parse_header;
    private $header;
    private $delimiter;
    private $length;

    function __construct($parse_header=false, $delimiter="\t", $length=8000) {
        add_shortcode( 'priceguide', array( $this, 'shortcode' ) );
        $this->parse_header = $parse_header;
        $this->delimiter = $delimiter;
        $this->length = $length;
    }

    public function shortcode($atts) {
        $attributes = shortcode_atts( array(
           'file' => '',
           'type' => '',
        ), $atts );

        if ( $attributes['type'] == "mods" ) {
            return $this->OpenMods($attributes['file']);
        }
    }

    function OpenMods($file) {
        return "test";
    }
}

PD: While developing you should have WP_DEBUG set to on and display errors set to on also; this way you would had seen a warning message saying that $attributes['mods'] is not set.