如何对Data:: dump的输出进行排序?

Question

我想转储我的对象和散列的值，但是它总是无序地打印键。如何以(递归)排序顺序转储键?

use Data::Dumper;
print Dumper $obj;

Answer 1

设置$Data::Dumper::Sortkeys = 1以获得Perl的默认排序顺序。如果您想自定义顺序，将$Data::Dumper::Sortkeys设置为对子例程的引用，该子例程接收对哈希的引用作为输入，并按照您希望的顺序输出对哈希键列表的引用。

# sort keys
$Data::Dumper::Sortkeys = 1;
print Dumper($obj);
# sort keys in reverse order - use either one
$Data::Dumper::Sortkeys = sub { [reverse sort keys %{$_[0]}] };
$Data::Dumper::Sortkeys = sub { [sort {$b cmp $a} keys %{$_[0]}] };
print Dumper($obj);

Answer 2

耐心的简短回答

请使用Data::Dumper::简明。它给你的钥匙分类。像这样使用:

use Data::Dumper::Concise;
my $pantsToWear = {
    pony       => 'jeans',
    unicorn    => 'corduroy',
    marsupials => {kangaroo => 'overalls', koala => 'shorts + suspenders'},
};
warn Dumper($pantsToWear);

更多好奇的单词

Data::Dumper::简洁也给你更紧凑，更容易阅读的输出。

注意Data::Dumper::简明是 Data::Dumper，为您设置了合理的默认配置值。它相当于像这样使用Data:: dump:

use Data::Dumper;
{
  local $Data::Dumper::Terse = 1;
  local $Data::Dumper::Indent = 1;
  local $Data::Dumper::Useqq = 1;
  local $Data::Dumper::Deparse = 1;
  local $Data::Dumper::Quotekeys = 0;
  local $Data::Dumper::Sortkeys = 1;
  warn Dumper($var);
}

Answer 3

您可以将$Data::Dumper::Sortkeys变量设置为真值以获得默认排序:

use Data::Dumper;
$Data::Dumper::Sortkeys  = 1;
my $hashref = {
    bob => 'weir',
    jerry =>, 'garcia',
    nested => {one => 'two', three => 'four'}};
print Dumper($hashref), "n";

或者在里面放一个子程序来排序你想要的键

Answer 4

来自Data::Dumper文档:

$Data::Dumper::Sortkeys or $OBJ->Sortkeys([NEWVAL])
Can be set to a boolean value to control whether hash keys are dumped in sorted order. 
A true value will cause the keys of all hashes to be dumped in Perl's default sort order. 
Can also be set to a subroutine reference which will be called for each hash that is dumped. 
In  this case Data::Dumper will call the subroutine once for each hash, passing it the 
reference of the hash. The purpose of the subroutine is to return a reference to an array of 
the keys that will be dumped, in the order that they should be dumped. Using this feature, you 
can control both the order of the keys, and which keys are actually used. In other words, this 
subroutine acts as a filter by which you can exclude certain keys from being dumped. Default is  
0, which means that hash keys are not sorted.

Answer 5

对于那些想要排序的hashref值使用Data::Dumper打印时，这里有一个例子:

$Data::Dumper::Sortkeys = sub {
    # Using <=> to sort numeric values
    [ sort { $_[0]->{$a} <=> $_[0]->{$b} } keys %{ $_[0] } ]
};

这里有一个更可读的替代方案，做同样的事情，但用一个变量来保存哈希值。它的效率较低，但对于小哈希，有些人可能会觉得它更好:

$Data::Dumper::Sortkeys = sub {
    my %h = %{$_[0]};
    # cmp for string comparisons
    [ sort { $h{$a} cmp $h{$b} } keys %h ];
};

Answer 6

排序ASCII和全数字:

$Data::Dumper::Sortkeys = sub {
  no warnings 'numeric';
  if(join('',keys %{$_[0]})=~/d+/)
  {
    [ sort { $a <=> $b } keys %{$_[0]} ]
  }
  else
  {
    return [sort(keys %{$_[0]})];
  }
};