golfing on localtime

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

It's annoying to use localtime. By default its output is kind of useless

perl -le 'print join(",", @{[localtime]}[5,4,3,2,1,0])'  
106,6,18,15,22,52
[download]

You have to add some extra statements to put it into more readable form:

perl -le '@_=localtime;
  print sprintf("%4d-%02d-%02d %02d:%02d:%02d",
                $_[5]+1900, $_[4]+1, @_[3,2,1,0])'
2006-07-18 15:57:36
[download]

But I'm wondering if there's a more compact way to do it (can be obfuscated), in one statement. Without cheating. For example:

perl -le'print join(",", (@_=@{[localtime]}[5,4,3,2,1,0])
                    && ($_[0]+1900, $_[1]+1, @_[2..5]))'
[download]

is obviously cheating, since the assignment and && basically make it into two statements (technically, no - but do you see the "spirit" of what I'm saying?). Can you do like a map on items in a list? I have something like this (non-working) in mind:

@t = (+ 1900, + 1, , , , ) = @{[localtime]}[reverse 0..5];
[download]

I'm guessing not but thought I'd ask.

(tiny update: I had the order reversed in the last example)

Comment on golfing on localtime Select or Download Code

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Re: golfing on localtime by davorg (Chancellor) on Jul 18, 2006 at 14:03 UTC
`perl -le 'print scalar localtime'` [download] Or if you're pickier about the format: `perl -MPOSIX=strftime -le 'print strftime "%Y-%m-%d %H:%M:%S", localti +me'` [download] Oh, and in your original code, `print sprintf` can be abbreviated to `printf`. -- <http://dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply] [d/l] [select]
Re: golfing on localtime by liverpole (Monsignor) on Jul 18, 2006 at 15:24 UTC
Hi ForgotPasswordAgain, Is this the kind of thing you're looking for ...? `+ # Golfed generation of current date/time @t=map{$_+{4,1,5,1900}->{5-$i++}}(reverse localtime)[3..8]; + # Print the date/time printf "%d-%d-%d %02d:%02d:%02d\n", @t;` [download] Update: Or even shorter (55 chars): `@t=map$_+{1,1,0,1900}->{$i++},(localtime)[5,4,3,2,1,0];` [download] (Update: Fixed typos in the above line). s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/	[reply] [d/l] [select]
Re^2: golfing on localtime by ForgotPasswordAgain (Vicar) on Jul 19, 2006 at 08:26 UTC
Ha, yes that's brilliant.	[reply]
Re: golfing on localtime by Corion (Patriarch) on Jul 18, 2006 at 14:03 UTC
I use the `strftime` function from the POSIX package for that - its only task is to give the output of `localtime` (and its siblings) a readable format: `perl -MPOSIX=strftime -e "print strftime '%Y-%m-%d %H:%M:%S',localtime +;" 2006-07-18 16:02:08` [download]	[reply] [d/l] [select]
Re: golfing on localtime by shmem (Chancellor) on Jul 18, 2006 at 15:22 UTC
Does this one pass as one statement for you? `perl -le 'print "@{[map{(localtime)[$c++]+$_}(0,0,0,0,1,1900,0,0,0)]}" +'` [download] You've got to get rid of $c afterwards, though. And yes, it calls localtime 9 times. But this was about golf, wasn't it? --shmem _($_=" "x(1<<5)."?\n".q·/)Oo. G°\ / /\_¯/(q / ---------------------------- \__(m.====·.(_("always off the crowd"))."· ");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}	[reply] [d/l]
Re: golfing on localtime by explorer (Chaplain) on Jul 18, 2006 at 14:23 UTC
I follow the standards of my old parents... `perl -MDateTime -le 'print DateTime->now' 2006-07-18T14:21:40` [download] Yes, I kown, is NOT localtime, but... is golfing!... and is the method recommended.	[reply] [d/l]
Re: golfing on localtime by ForgotPasswordAgain (Vicar) on Jul 18, 2006 at 14:25 UTC
Sorry, in trying to "motivate" the problem, I've managed to explain the question badly. I know about `strftime`, it's right in the perldoc for `localtime`. What I was more interested in was the question at the end. I was just curious if there was some goatse-operator-esque way of tweaking a list without going through an intermediary variable. I know, it's a stupid question.	[reply] [d/l] [select]
Re^2: golfing on localtime by Corion (Patriarch) on Jul 18, 2006 at 14:30 UTC
As long as you only have adjustments of numbers, I'd go for List::MoreUtils' `zip` function: `my @adjustments = ( +1900, +1, 0, 0, 0, 0, ); my @t = pairwise { $a+$b } @adjustments, @{[localtime]};` [download] If the operation differs between the elements of the target list/array, I guess a multi-map / MapCar is what you'll need: `my @adjustments = ( sub { $_[0] + 1900 }, sub { $_[0] + 1 }, sub { $_[0] + 0 }, ... ); my @t = pairwise { $a->($b) } @adjustments, @{[localtime]};` [download]	[reply] [d/l] [select]