I did smack my daughter when she was a toddler if she was putting herself in danger and could not understand that. When she was older and wouldn't do as she was told I would sit her down and explain she could do it now with the minimum of fuss or she could refuse, get a smack, we'd both get upset and she'd still have to do it anyway. That was usually enough to get her to behave. I don't agree with parents smacking their kids because they can't be bothered trying to reason, or because they've lost their temper or worst of all because they think it 'commands respect'. But when a child is in danger a small tap on the hand (which usually gives them more of a shock than anything) is preferable to them sticking a finger in the socket or something.