Another possible style, which I prefer, consists in writing the comma at the beginning of the next line, not the end of the previous one.

That reminds me of the professor who gave us our first programming classes back in university. He would write the semi-colons before the statements, not after them. (This was in Pascal, where semi-colons are statement separators, just like in Perl).

This style also allows easier editing of the hash.

Really? How? I see as disadvantage that if you remove the first item you need to modify the next line. Or if you insert an item at the beginning, you need to modify the next line too. The big advantage of putting a comma after the items is that you can always put a comma there, and don't have to do special things when adding or removing elements - not even at the beginning or end.

Abigail