添加到表现异常的 Perl 哈希

我试图通过将时间标签从事件内移动到其父级内来更改一些 XML 以按时间对事件进行分组。那是...

<schedule>
    <event>
        <time>02:00</time>
        <other_details>details</other_details>
    </event>
    <event>
        <time>02:00</time>
        <other_details>details</other_details>
    </event>
    <event>
        <time>03:00</time>
        <other_details>details</other_details>
    </event>
<schedule>

应该成为

<schedule>
    <event>
        <time>02:00</time>
        <event_details>
            <other_details>details</other_details>
        </event_details>
        <event_details>
            <other_details>details</other_details>
        </event_details>
    </event>
    <event>
        <time>03:00</time>
        <event_details>
            <other_details>details</other_details>
        </event_details>
    </event>
</schedule>

我解决这个问题的方法是使用 XML::Simple 将 XML 读入散列，抽出时间，并将其用作另一个散列的键，该散列包含一组event_details. Code:

#!/Perl/bin/perl
#scheduleConversion.plx v1.0

use strict;
use warnings;

use XML::Simple;
use Data::Dumper;

use constant EVENTTAG   => 'event';
use constant TIMETAG    => 'event_time';
use constant DETAILSTAG => 'event_details';

if($#ARGV != 0) {
    print "Usage: First argument should be filename, optionally with path.";
}

# Get filename/path from the arguments
my $docname = shift @ARGV;

# Create a new XML parser
my $xml = new XML::Simple;
# Read in the XML data
my $XMLdata = $xml->XMLin($docname);
# New XML data to be output
my %XMLnew;
$XMLnew{&EVENTTAG} = [];

my %timeGroups;

foreach (@{$XMLdata->{&EVENTTAG}}) {
    my $time = ${$_}{&TIMETAG};
    delete ${$_}{&TIMETAG};

    # Make an array if none exists
    $timeGroups{$time} = [] unless exists($timeGroups{$time});
    # Add our details to the array
    push($timeGroups{$time}, $_);
}

foreach (%timeGroups) {
    push ($XMLnew{&EVENTTAG}, $_{&EVENTTAG});
}

#print $xml->XMLout(%XMLnew);

问题是当我尝试print Dumper(%timeGroups);，它给了我这样的结果：

$VAR1 = '2015-09-10 03:59:00';
$VAR2 = [
          {
            'event_detail_1' => 'details_1',
            'event_detail_2' => 'details_2'
          }
        ];

我希望看到日期作为关键，但它似乎是一个完全不同的条目。我用一个单独的哈希测试了这个，还创建了一个键/值对$hash{key} = 'value'，这给出了与上面相同的意外结果，而$hash = {'key' => 'value'}给出了预期的结果。
我确信我只是错过了有关 Perl 哈希如何工作的一些内容，但我认为这两种方法应该是等效的。我一整天都在用我的大脑思考这个问题，我刚刚设法将其范围缩小到这个原因。

print Dumper(%timeGroups)正在变平%timeGroups放入键和值的列表中并将多个参数传递给Dumper。通常你想向 Dumper 传递一个引用：print Dumper(\%timeGroups).