I smack when it comes to danger. I have recently just once smacked DS on the hand as he was playing with a power point.
Now I don't really agree with it, but I'd tried moving him & distracting him, but he kept going back to it. I didn't do it hard enough for it to register, it actually just distracted him coz he'd never seen it before, & finally the power point was forgotten about.

When DD1 was 2 she worked out how to open the screen door. One day she took off up the road. I tried calling her & ended up having to run & get her. I took her home & gave her a smack on the bum & told her she was naughty etc.
The next day she did it again. This time she kept running up & around the corner. I was lucky that she'd had it drilled into her head that the road was very dangerous & never walked on it, but this time I smacked her as soon as I got her, there on the corner. She scared the life out of me.
She never did it again after that.

I don't like smacking & very rarely do it. DH & I used to fight about it constantly as he believes a child needs it & more.
If I'm in public I have grabbed Jaz firmly on the wrist. She can be a real handful in public coz she thinks she can get away with it & will get Bri to run off in the shops or will try a tanty on.
So I am guilty of grabbing her by the wrist or arm even & getting down to warn her not to do what ever it is.
Honestly I don't like doing it & I don't think I would ever do it to Bri, but she's a different child. She'll react to me saying we will go home, or me taking something away for the day. Jaz isn't fazed in the slightest.
I packed a room full of toys into a garbage bag 12 months ago because after like 3 weeks she still refused to clean them & she just shrugged her shoulders.
So I believe that each child is different. Things work differently for every family & every child. Hopefully Jaz will stop being so difficult soon, but she is stuck on the fact that her & Bri aren't treated exactly the same.
She thinks that if I get Bri drinks during the day, or for bed that I should get her one too. She is nearly 7 & should be starting to do these things herself, but refuses coz her 3 year old sister doesn't have to.
I was smacked. It didn't bother me. I knew what was right & wrong, I knew there were consequenses for my actions, & I'm far from violent now. I never have been. Neither are my brother or sister.
I think everyone is different & as long as a child isn't actually hurt form the force I think parents should be able to choose how they discipline.