Magento setCouponCode

Question

Is there anyone know where i can find the setCouponCode function is?
Cause what im trying to do is, i want to add some custom code when adding the coupon code where i added table in the database that has my custom code to be check. I believe that Magento is checking the database before setting the coupon code thats why when i apply my custom code even its apply the Cancel Coupon does not show in my view.
Actually i can do this by editing my view but this i want it to be dynamic that even i apply this module to new store, it doesnt affect the view page.
Hope you understand my long explanation and i hopping someone can help me this problem.

Answer 1

setCouponCode is a magic function within magento, so there is no defining function. Typically when you see setCouponCode there is usually a collectTotals function right after. That is what validates the coupon code and calculates all the prices.