A motorist punched another driver's hand in a road-rage incident as the victim tried to record him on his phone.
Simon Lawlor (26) lashed out and hit the man during a parking dispute.
The row started after Lawlor left his car blocking an entrance while he went on a shopping errand for his pregnant partner.
Judge John Hughes applied the Probation Act, leaving him without a conviction.
The judge said the accused had simply "lost the head" while under stress.
Lawlor, of Orwell Park View, Templeogue, pleaded guilty to assault.
Gda Keith Branigan told Dublin District Court that the incident happened in Whitehall Road West, Perrystown, on April 30 last year.
Lawlor's vehicle was blocking the entrance to a laneway the victim was trying to exit. He was beeping his horn as he could not access the main road as a result.
There was an altercation between the accused and victim, who started shouting at each other.
The victim attempted to record Lawlor on his phone during the dispute, and the accused punched him on the hand and then "took off".
Defence barrister Joseph Mulrean said the incident was a "flash in the pan" and Lawlor was sorry.
Judge Hughes asked why Lawlor did not move instead of "lashing out with his fist".
Mr Mulrean said the defendant had been in the Ashleaf Centre buying something for his pregnant partner.
He was not there long and "fundamentally, I think there was a problem of a lack of patience on both sides", Mr Mulrean said.
Judge Hughes noted a probation report stated Lawlor was at a low risk of re-offending.
"It appears to be one of those unfortunate incidents where two people who are under stress encounter each other and matters got out of hand," he said.
There was no injury intended or sustained, the judge added.
Blood was running high and Lawlor "simply lost the head".
Dismissing the charge, the judge said he did not want to harm Lawlor's employment prospects.