calling variable from another classes function

Question

I have a class called ot_lev_discount

in that class I have a function:

    <?php
/*
<<<<<<< ot_lev_discount.php
  $Id: ot_lev_discount.php,v 1.0 2002/04/08 01:13:43 hpdl Exp $
=======
  $Id: ot_lev_discount.php,v 1.3 2002/09/04 22:49:11 wilt Exp $
  $Id: ot_lev_discount.php,v 2.4 2006/02/28 12:10:01 maniac101 Exp $
modified to calc discount correctly when tax is included in discount
>>>>>>> 2.4

  osCommerce, Open Source E-Commerce Solutions
  http://www.oscommerce.com

  Copyright (c) 2002 osCommerce

  Released under the GNU General Public License
*/

  class ot_lev_discount {
    var $title, $output;

    function ot_lev_discount() {
      $this->code = 'ot_lev_discount';
      $this->title = MODULE_LEV_DISCOUNT_TITLE;
      $this->description = MODULE_LEV_DISCOUNT_DESCRIPTION;
      $this->enabled = MODULE_LEV_DISCOUNT_STATUS;
      $this->sort_order = MODULE_LEV_DISCOUNT_SORT_ORDER;
      $this->include_shipping = MODULE_LEV_DISCOUNT_INC_SHIPPING;
      $this->include_tax = MODULE_LEV_DISCOUNT_INC_TAX;
      $this->calculate_tax = MODULE_LEV_DISCOUNT_CALC_TAX;
      $this->table = MODULE_LEV_DISCOUNT_TABLE;
//      $this->credit_class = true;
      $this->output = array();
    }

    function process() {
      global $order, $ot_subtotal, $currencies;
      $od_amount = $this->calculate_credit($this->get_order_total());
      if ($od_amount>0) {
      $this->deduction = $od_amount;
      $this->output[] = array('title' => $this->title . ':',
                              'text' => '<b>' . $currencies->format($od_amount) . '</b>',
                              'value' => $od_amount);
    $order->info['total'] = $order->info['total'] - $od_amount;
    if ($this->sort_order < $ot_subtotal->sort_order) {
      $order->info['subtotal'] = $order->info['subtotal'] - $od_amount;
    }
}
    }


  function calculate_credit($amount) {
    global $order;
    $od_amount=0;
    $table_cost = split("[:,]" , MODULE_LEV_DISCOUNT_TABLE);
    for ($i = 0; $i < count($table_cost); $i+=2) {
          if ($amount >= $table_cost[$i]) {
            $od_pc = $table_cost[$i+1];
          }
        }
// Calculate tax reduction if necessary
    if($this->calculate_tax == 'true') {
// Calculate main tax reduction
      $tod_amount = round($order->info['tax']*10)/10*$od_pc/100;
      $order->info['tax'] = $order->info['tax'] - $tod_amount;
// Calculate tax group deductions
      reset($order->info['tax_groups']);
      while (list($key, $value) = each($order->info['tax_groups'])) {
        $god_amount = round($value*10)/10*$od_pc/100;
        $order->info['tax_groups'][$key] = $order->info['tax_groups'][$key] - $god_amount;
      }  
    }


   $od_amount = $od_pc;
   // if you want to use %age instead of flat amount:  $od_amount = round($amount*10)/10*$od_pc/100;


//    $od_amount = $od_amount + $tod_amount;
// maniac101 above line was adding tax back into discount incorrectly for me
    return $od_amount;
  }


  function get_order_total() {
    global  $order, $cart;
    $order_total = $order->info['total'];
// Check if gift voucher is in cart and adjust total
    $products = $cart->get_products();
    for ($i=0; $i<sizeof($products); $i++) {
      $t_prid = tep_get_prid($products[$i]['id']);
      $gv_query = tep_db_query("select products_price, products_tax_class_id, products_model from " . TABLE_PRODUCTS . " where products_id = '" . $t_prid . "'");
      $gv_result = tep_db_fetch_array($gv_query);
      if (ereg('^GIFT', addslashes($gv_result['products_model']))) { 
        $qty = $cart->get_quantity($t_prid);
        $products_tax = tep_get_tax_rate($gv_result['products_tax_class_id']);
        if ($this->include_tax =='false') {
           $gv_amount = $gv_result['products_price'] * $qty;
        } else {
          $gv_amount = ($gv_result['products_price'] + tep_calculate_tax($gv_result['products_price'],$products_tax)) * $qty;
        }
        $order_total=$order_total - $gv_amount;
      }
    }
    if ($this->include_tax == 'false') $order_total=$order_total-$order->info['tax'];
    if ($this->include_shipping == 'false') $order_total=$order_total-$order->info['shipping_cost'];
    return $order_total;
  }   



    function check() {
      if (!isset($this->check)) {
        $check_query = tep_db_query("select configuration_value from " . TABLE_CONFIGURATION . " where configuration_key = 'MODULE_LEV_DISCOUNT_STATUS'");
        $this->check = tep_db_num_rows($check_query);
      }

      return $this->check;
    }

    function keys() {
      return array('MODULE_LEV_DISCOUNT_STATUS', 'MODULE_LEV_DISCOUNT_SORT_ORDER','MODULE_LEV_DISCOUNT_TABLE', 'MODULE_LEV_DISCOUNT_INC_SHIPPING', 'MODULE_LEV_DISCOUNT_INC_TAX','MODULE_LEV_DISCOUNT_CALC_TAX');
    }

    function install() {
      tep_db_query("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, set_function, date_added) values ('Display Total', 'MODULE_LEV_DISCOUNT_STATUS', 'true', 'Do you want to enable the Order Discount?', '6', '1','tep_cfg_select_option(array(\'true\', \'false\'), ', now())");
      tep_db_query("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, date_added) values ('Sort Order', 'MODULE_LEV_DISCOUNT_SORT_ORDER', '999', 'Sort order of display.', '6', '2', now())");
      tep_db_query("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, set_function ,date_added) values ('Include Shipping', 'MODULE_LEV_DISCOUNT_INC_SHIPPING', 'true', 'Include Shipping in calculation', '6', '3', 'tep_cfg_select_option(array(\'true\', \'false\'), ', now())");
      tep_db_query("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, set_function ,date_added) values ('Include Tax', 'MODULE_LEV_DISCOUNT_INC_TAX', 'true', 'Include Tax in calculation.', '6', '4','tep_cfg_select_option(array(\'true\', \'false\'), ', now())");
      tep_db_query("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, set_function ,date_added) values ('Calculate Tax', 'MODULE_LEV_DISCOUNT_CALC_TAX', 'false', 'Re-calculate Tax on discounted amount.', '6', '5','tep_cfg_select_option(array(\'true\', \'false\'), ', now())");
      tep_db_query("insert into " . TABLE_CONFIGURATION . " (configuration_title, configuration_key, configuration_value, configuration_description, configuration_group_id, sort_order, date_added) values ('Discount Percentage', 'MODULE_LEV_DISCOUNT_TABLE', '100:7.5,250:10,500:12.5,1000:15', 'Set the price breaks and discount percentages', '6', '6', now())");
    }

    function remove() {
      $keys = '';
      $keys_array = $this->keys();
      for ($i=0; $i<sizeof($keys_array); $i++) {
        $keys .= "'" . $keys_array[$i] . "',";
      }
      $keys = substr($keys, 0, -1);

      tep_db_query("delete from " . TABLE_CONFIGURATION . " where configuration_key in (" . $keys . ")");
    }

  }
?>

I want to echo the $od_amount variable from a different php file so I did the following to no avail:

require(DIR_WS_MODULES . 'order_total/ot_lev_discount.php');
$ot_lev_discount = new ot_lev_discount();

echo $ot_lev_discount->od_amount;

I seem to be able to call the classes global variables in this way but not the ones in the classes function.

What's in the constructor? And what does $ot_lev_discount->od_amount return? Is $od_amount a property of ot_lev_discount? It would help if you posted more (all) of the class. — Michael
– Michael, Commented Mar 6, 2013 at 15:07
Variables in a class method are scoped to that method, so not accessible outside; in exactly the same way that local varaibles in a normal function are scoped to that function.... why did you think otherwise? — Mark Baker
– Mark Baker, Commented Mar 6, 2013 at 15:07
I added the entire class to look at. $ot_lev_discount->od_amount isn't returning anything. At least not when I echo it like I am? I'm not sure what you mean by is it a property of ot_lev_discount — Sackling
– Sackling, Commented Mar 6, 2013 at 15:11
@MarkBaker I'm pretty new to oop so I am figuring things out as I go along — Sackling
– Sackling, Commented Mar 6, 2013 at 15:12
Really, try to remove all those global needs & go for function parameters, and set class properties & proper returns. Globals like this are evil without question (there's a time & place for them, this ain't it). — Wrikken
– Wrikken, Commented Mar 6, 2013 at 15:12

Voitcus · Accepted Answer · 2013-03-06 15:07:35Z

1

global does not make a variable being a property of a class, it only tells that this value can be used in any method of it.

You can make work around this, see this example

answered Mar 6, 2013 at 15:07

Voitcus

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Comments

Michal Trojanowski · Accepted Answer · 2013-03-06 15:10:50Z

By calling $ot_lev_discount->od_amount you are trying to get the od_amount propery of your class, but your class doesn't have one.

You need to modify your class like this:

class ot_lev_discount  {

    ...

    public $od_amount;

    function calculate_credit($amount)
    {
         ...
         $this->od_amount = $od_amount;

         return $od_amount;
    }

}

This way you will be able to access the property using $ot_lev_discount->od_amount. Of course its value will be null unless you call the $ot_lev_discount->calculate_credit() function.

Take some time to read the documentation on classes, objects, their properties and variable scopes. It should shed some light onto the problems you are facing (and these are general Object Oriented Programming topics, not solely conected to PHP).

anthony_mcdougle · Accepted Answer · 2013-03-06 15:12:17Z

0

Variables within the function have a local scope of that function, and cannot be called from outside the function. You could make these variables' scope class-level and public by doing the following:

class ot_lev_discount {
    public $od_amount;
    ....
}

And then you can access the variable as such:

$var = new ot_lev_discount();
$var->od_amount;

Although, in this case, every time you create a new object, that object will have its own od_amount variable, which is not the same as another object of the same class and won't have the same value unless you perform the same calculations on it.

Alternatively, call the function and get the return value.

answered Mar 6, 2013 at 15:12

anthony_mcdougle

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8 Comments

Sackling Over a year ago

OK I tried making $od_amount public but i get a T_PUBLIC parse error. I am going to try and call the function and get the return value but I'm not too sure how to do that, because it requires the $amount otherwise I get the "missing argument" error

Michal Trojanowski Over a year ago

You must declare the property outside of the function but inside the class. You can't set a public property inside of a function.

Sackling Over a year ago

I tried doing that also and when I echo it from the second class it has no amount.. So it needs to be done with your alternate suggestion I think so that the amount is calculated, and then I when $od_amount is returned I want to echo that.. I just can't figure out how to do that

anthony_mcdougle Over a year ago

Like I said -- two objects of the same class are not the same variable, and will have different values for the variables within their scope. $var1 = new od_lev_discount(); $var2 = new od_lev_discount; $var1->od_amount = 3; // $var2->od_amount is still empty. You can also look up Singleton classes if you want the value to remain static between all instances of the class.

Sackling Over a year ago

So what I am trying to accomplish is to get that variable with the same value from the calculate_credit function. Do I need to make a get function that returns that? I'm a bit lost.

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