app/etc/modules/Gta_KolupadiRestrict.xml

<?xml version="1.0" encoding="UTF-8"?>
<config>
    <modules>
        <Gta_KolupadiRestrict>
            <active>true</active>
            <codepool>local</codepool>
        </Gta_KolupadiRestrict>
    </modules>
</config>
app/code/local/Gta/KolupadiRestrict/etc/config.xml

 

<?xml version="1.0"?>
<config>
    <modules>
        <Gta_KolupadiRestrict>
            <version>1.0.0</version>
        </Gta_KolupadiRestrict>
    </modules>
    <global>
        <models>
            <gta_kolupadirestrict>
                <class>Gta_KolupadiRestrict_Model</class>
            </gta_kolupadirestrict>
        </models>
    </global>   
    <frontend>
        <events>
            <checkout_cart_product_add_after>
                <observers>
                    <Gta_KolupadiRestrict_Model_Observer>   
                        <type>singleton</type>
                        <class>Gta_KolupadiRestrict_Model_Observer</class>
                        <method>cartevent</method>
                    </Gta_KolupadiRestrict_Model_Observer>
                </observers>
            </checkout_cart_product_add_after>      
        </events>
    </frontend>
</config>
app/code/local/Gta/KolupadiRestrict/Model/Observer.php
<?php
    // Mage::log('fine dude', null, 'logfile.log');
    //create class
    class Gta_KolupadiRestrict_Model_Observer
    {   
        //create function
        public function cartevent(Varien_Event_Observer $observer)
        {
        
            $event = $observer->getEvent();
            Mage::log($event->getName(),null,'event.log');

        }       
    }
?>