I don't like the comma-prepending style. You can easily add a new line at the bottom that way, but not at the top. It might be fine for languages that are inflexible about their commata, but Perl is not - you can append one to the last value with no harm. My formatting looks like this:
in reply to Re^2: Tact and the Monastery
in thread Tact and the Monastery
Note the "errant" comma after the last value. Separating the assignment and closing bracket on their own lines adds more convenience. This way, I can add a hash key anywhere - even at the bottom or the top - without having to edit any other line than the one I'm on.
my %hash = (
one => 1,
two => 2,
three => 3,
Makeshifts last the longest.