What is the recommended way of doing date arithmetics in Perl?

Question

What is the recommended way of doing date arithmetics in Perl?

Say for example that I want to know the date three days ago from today (where today = 2010-10-17 and today - 3 days = 2010-10-13). How would you do that in Perl?

Solution 1

You can use DateTime and DateTime::Duration

http://search.cpan.org/dist/DateTime/lib/DateTime/Duration.pm

Or work with unix timestamps:

my $now = time();
my $threeDaysAgo = $now - 3 * 86400;
my ($day, $mon, $year) = (localtime($threeDaysAgo))[3, 4, 5];
printf("Three days ago was %04d-%02d-%02d", $year+1900, $mon+1, $day);

Solution 2

See DateTime on CPAN (or here).

Solution 3

There are many, many different date and time manipulation modules.

These include:

• Date::Calc - and the Add_Delta_Days function
• Date::Manip - and the DateCalc function
• DateTime

All of these are well thought of. There are many others in addition. A lot depends on the sort of arithmetic you want to do. DateTime is perhaps the most rigorous, but Date::Calc and Date::Manip may be easier to handle for the work you need.

Comments

[plusplus]

you don't even need to bother with DateTime::Duration itself for a lot of date manipulation, e.g. $three_days_ago = DateTime->now()->subtract( days => 3 )

[OMG_peanuts]

The only thing to take care, using DateTime, is to minimize the number of DateTime objects you instantiate (could be pretty time consuming to allocate and destroy). Reuse as often as possible.