I once wrote a module to do this (long before DateTime).
Note that in the second case the result is exact.
Date::Tie is _very_ careful to round errors correctly.
use Date::Tie;
tie my %date, 'Date::Tie', frac_hour => 2.67;
print $date{frac_hour}, "\n";
print $date{hour}, ":",
$date{minute}, ":",
$date{frac_second}, "\n";
# 02.67
# 02:40:12.0
$date{frac_hour} = 2 + 2/3;
print $date{frac_hour}, "\n";
print $date{hour}, ":",
$date{minute}, ":",
$date{frac_second}, "\n";
# 02.66666666666667
# 02:40:00.0
- Flavio S. Glock
