magento event listener - events

Question

I don't want to apply the discount coupon on the products already discounted i.e on products having special price . So i created a event listen as :
<?xml version="1.0" ?>
<config>
<modules>
<Tweett_Fashionn>
<version>0.1.0</version>
</Tweett_Fashionn>
</modules>
<global>
<events>
<salesrule_validator_process>
<observers>
<Tweett_Fashionn_Hook>
<type>singleton</type>
<class>Tweett_Fashionn_Model_Observer</class>
<method>specialpricediscount</method>
</Tweett_Fashionn_Hook>
</observers>
</salesrule_validator_process>
</events>
</global>
and the observer file as
<?php
class Tweett_Fashionn_Model_Observer extends Varien_Event_Observer{
public function __construct(){
echo "<p style='color:red'>Hello World .. </p>";
}
public function specialpricediscount($observer){
$item=$observer['item'];
$_product = Mage::getSingleton('catalog/product')->load($item->getProductId());
if($_product->getSpecialPrice()>0 ){
$result = $observer['result'];
$result->setDiscountAmount(0);
}
}
}
?>
but it dont even print the hello world when i click on apply coupon button ..plz help

Answer 1

You're missing the ending from your config.xml? You may have just not pasted it in.
Have you made sure your module is enabled?
Take a look at this free extension it can help you debug extensions - http://www.magentocommerce.com/magento-connect/magneto-debug-8676.html

Answer 2

I had same issue.I think following is correct way :
<salesrule_validator_process>
<observers>
<Namespace_Modulename> // your namespace_modulename
<type>model</type> //change singleton to model
<class>Tweett_Fashionn_Model_Observer</class>
<method>specialpricediscount</method>
</Namespace_Modulename>
</observers>
</salesrule_validator_process>
May this will help you.