Re: code to get the date for "next Thursday"

[Albannach]

Again it might not be any faster, but it is useful to note that ParseDate is smarter than you think:

Use Date::Manip;
print UnixDate(ParseDate('next thursday'),'%A %e %b %Y'),"\n";

gives Thursday 23 Mar 2006

Update: Here's a method using the usually-faster Date::Calc and a benchmark of some of the offerings... any guesses as to why Date::Manip is soooo slow? (1.7GHz P4 Win2k, 256MB RAM)

           Rate   Manip    bfdi ikegami    Calc
Manip     216/s      --     -7%    -99%   -100%
bfdi      231/s      7%      --    -99%   -100%
ikegami 29540/s  13596%  12701%      --    -65%
Calc    84063/s  38874%  36327%    185%      --

Code follows:

use strict;
use warnings;
use Benchmark qw(cmpthese);
use Date::Manip;
use Date::Calc qw(Today Day_of_Week Add_Delta_Days);

Date_Init('TZ=EDT');

# for ikegami
use POSIX       qw( strftime       );
use Time::Local qw( timegm_nocheck );

sub ikegami {
  my ($day, $mon, $year, $wday) = (localtime())[3..6];  # Defaults to 
+now.

  $year += 1900;
  $day  += (7 - $wday + 4) % 7;
  my $next_th = timegm_nocheck(0,0,0,$day,$mon,$year); # fixed, was $m
+day rather than $day

  return strftime('%Y-%m-%d', gmtime($next_th));
}

sub bfdi533 {
  my $today_dt = &ParseDate("today");
  my $new_dt = &Date_GetNext($today_dt, 'Thu', 1);
  my $date = &UnixDate($new_dt, "%Y-%m-%d");
}

sub Manip {
  return UnixDate(ParseDate('next thursday'),'%Y-%m-%e');
}

sub Calc {
  my($year,$month,$day) = Today();
  my $nextday = 4; # Thursday
  my $dow = Day_of_Week($year,$month,$day);
  my $delta = (7 + $nextday - $dow) % 7;
  my ($y,$m,$d) = Add_Delta_Days($year, $month, $day, $delta);
  return sprintf('%4i-%02i-%02i', $y, $m, $d);
}

cmpthese(-3, {
  bfdi    => \&bfdi533,
  ikegami => \&ikegami,
  Manip   => \&Manip,
  Calc    => \&Calc,
  } );