Way to calculate day-of-the-week

sylph001 has asked for the wisdom of the Perl Monks concerning the following question:

Replies are listed 'Best First'.
Re: Way to calculate day-of-the-week by hippo (Archbishop) on Dec 24, 2014 at 11:11 UTC
"best" is subjective of course. Ordinarily I would use Time::Piece as it is core. It comes with the `day_of_week` method which does what you intend and uses `strptime` for date parsing. However, this task is very much TIMTOWTDI. There are a plethora of date and time parsing/manipulation modules and it pays to be at least passingly familiar with the most popular ones.	[reply] [d/l] [select]
Re: Way to calculate day-of-the-week by blindluke (Hermit) on Dec 24, 2014 at 09:20 UTC
Hello. There is a great module (meta-module) called Task::Kensho, that groups tried things that people use for common purposes under one umbrella. Look at the Dates section for modules related to Dates. I would recommend DateTime, with the following usage (from module synopsis): `use DateTime; $dt = DateTime->new( year => 1964, month => 10, day => 16, ); $dow = $dt->day_of_week; # 1-7 (Monday is 1)` [download] - Luke	[reply] [d/l]
Re^2: Way to calculate day-of-the-week by BillKSmith (Monsignor) on Dec 24, 2014 at 13:44 UTC
I have never had a time related problem that I could not do with Date::Time. It probably is always overkill, but it gets the job done. Why look further? Bill	[reply]
Re^3: Way to calculate day-of-the-week by blindluke (Hermit) on Dec 24, 2014 at 21:29 UTC
There are some reasons you won't find Date::Time under the Task::Kensho modules. For one, look at this review of the module you mentioned. Or the fact that the module synopsis still starts with the line: This is just some suggestions, as nothing is implemented yet. I'm open to critisism. The fact that you 'never had a time related problem' that you could not do with one particular tool is still not enough to be sure that there is no reason to look further into other tools. Even curiosity is reason enough to look further. As always, TIMTOWTDI. - Luke	[reply]
Re^4: Way to calculate day-of-the-week by Your Mother (Archbishop) on Dec 25, 2014 at 01:43 UTC
Re^5: Way to calculate day-of-the-week by blindluke (Hermit) on Dec 25, 2014 at 10:59 UTC
Re: Way to calculate day-of-the-week by Anonymous Monk on Dec 25, 2014 at 00:04 UTC
localtime, Time::Piece, DateTime, Date::Calc or Date::Manip. Time::Piece is in the core since v5.10; personally I prefer DateTime since that's covered all my needs so far (including the DateTime::Format:: family), although some people find it a little too heavyweight (just something to consider and test out in case you plan on doing many calculations like this).	[reply]
Re: Way to calculate day-of-the-week by clueless newbie (Curate) on Dec 24, 2014 at 13:03 UTC
Super simple ... no modules - just a few arithmetic operations! Day of week for an arbitrary date using core modules	[reply]
Re^2: Way to calculate day-of-the-week by Anonymous Monk on Dec 24, 2014 at 23:48 UTC
Please, please, please don't encourage people to do this when there are perfectly good, well-maintained, well-tested date/time modules available to do the task. People copy-pasting or re-inventing their own date/time routines is an incredibly common source of bugs and maintenance nightmares.	[reply]
Re^3: Way to calculate day-of-the-week by locked_user sundialsvc4 (Abbot) on Dec 28, 2014 at 18:26 UTC
Y’see? If you had logged-in, you would have accumulated 17 experience-points and counting.) This is fundamentally excellent advice. If you “roll your own” solution to [any ...] “well-known Thing That Has Already Been Done™,” merely to avoid installing and `use`ing a well-known CPAN module that does the entire task, then you have imposed an unnecessary maintenance burden upon the future maintainers of your code. (“Goody for you that you now work at Google, but I’m still here ...”) If you had used the CPAN tool, then your successors would not have to dumpster-dive into that piece of logic ~~to be sure that you did it right~~ to discover the subtle bug in your one-of-a-kind code. Instead, they could have relied upon the self-tests that the CPAN module includes, knowing that the module would not have been installed at all if any of those self-tests had failed. Also: if you are maintaining a legacy code-base that did these things in a particular way, e.g. using a CPAN module that you really don’t like but that does do the job correctly, please “keep using that module.” Don’t unnecessarily introduce “two sources of Truth.”