Perl DateTime subtract_datetime_absolute有趣的行为

Question

这是一个DateTime错误还是我错过了什么？

sub get_diff_same_day { 
    # return only the time difference between 2 dates 
    my ($dnow, $dt) = @_; 
    my $dtx = $dt->clone(); 
    $dtx->set_year($dnow->year); 
    $dtx->set_month($dnow->month); 
    $dtx->set_day($dnow->day); 
    say $dnow; 
    say $dtx; 

    return $dtx->subtract_datetime_absolute($dnow); 
} 

输出：

2012-04-18T09:56:39 
2012-04-18T09:56:40 

0 DateTime::Duration=HASH(0x1e10a34) 
    'days' => 0 
    'end_of_month' => 'wrap' 
    'minutes' => 0 
    'months' => 0 
    'nanoseconds' => 0 
    'seconds' => 3577  # <= huh? 

然而，不是如果我用subtract_datetime_absolute

$dtx - $dnow 

这给了我：

0 DateTime::Duration=HASH(0x1bada04) 
    'days' => 0 
    'end_of_month' => 'wrap' 
    'minutes' => 0 
    'months' => 0 
    'nanoseconds' => 0 
    'seconds' => 1 

这在我看来，subtract_datetime_absolute没有按”请考虑DateTime :: set_xxxx函数。

编辑：下面的示例。

use Modern::Perl; 
use autodie; 
use DateTime; 


use constant OFFSET => 0; 

## main 
test(); 

sub test { 
    my $now = DateTime->now(time_zone => 'local')->add(hours => OFFSET); 
    my $ddt = get_rand_date(); 
    my $secs = get_secs_same_day_broken ($now, $ddt); 
    my $secs2 = get_secs_same_day($now, $ddt); 

    if ($secs != $secs2) { 
    say "expecting same result ($secs, $secs2)"; 
    } 
} 

sub get_secs_same_day_broken { 
    # return the seconds time difference between 2 dates 
    my ($dnow, $dt) = @_; 
    my $dtx = $dt->clone(); 
    $dtx->set_year($dnow->year); 
    $dtx->set_month($dnow->month); 
    $dtx->set_day($dnow->day); 
    say "A: $dnow vs $dtx"; 
    return $dtx->subtract_datetime_absolute($dnow)->seconds; 
} 

sub get_secs_same_day { 
    # return the seconds time difference between 2 dates 
    my ($dnow, $dt) = @_; 
    my $dtx = $dt->clone(); 
    $dtx->set_year($dnow->year); 
    $dtx->set_month($dnow->month); 
    $dtx->set_day($dnow->day); 
    say "B: $dnow vs $dtx"; 
    return ($dtx - $dnow)->seconds; 
} 

sub get_rand_date { 
    my $d = int(rand(27)) + 1; 
    my $M = int(rand(11)) + 1; 
    my $h = int(rand(24)); 
    my $m = int(rand(60)); 
    my $s = int(rand(60)); 

    my $dt = DateTime->new(day => $d, month => $M, year => 2012, hour => $h, minute => $m, second => $s); 
    $dt->add(hours => OFFSET); 

    return $dt; 
} 

Answer 1

$dtx->subtract_datetime_absolute($now)->seconds返回两个日期为秒的绝对数目之间的差。

试试这个：

my $now = DateTime->now(time_zone => 'local'); 
my $dtx = $now->clone->set(hour => 22, minute => 22, second => 22); 

{ 
    use integer; 
    my $seconds = $dtx->subtract_datetime_absolute($now)->seconds; 
    my $minutes = $seconds/60; 
    say $seconds - ($minutes * 60); 
} 

{ 
    my $seconds = ($dtx - $now)->seconds; 
    say $seconds; 
}