Wolly liberal comment ahead.
I will never hit my son to discpline him. In my opinion, it only teaches children that violence is a way to solve problems and impose respect.
There are far easier ways to discpline any child: they all want things it may be a toy, or a food treat such as ice cream etc. Denying them these pleasures is carries far more influence on their behaviour. The key is to follow through with your threats and keeping your discpline. Smacking is, again in my opinion, just a excuse for lazy parenting, as the other tehcniques require far more work.