I have two Perl packages: pack_hash and pack_run
package pack_hash;
$VERSION = '1.00';
@ISA = qw( Exporter );
@EXPORT_OK = qw( %hashInfo );
$hashInfo{abc} = ['a', 'b', 'c'];
1;
package pack_run;
use stricts;
use warnings;
use Data::Dumper;
use pack_hash qw( %hashInfo );
somethingDoing();
sub somethingDoing {
my $var1 = \%pack_hash::hashInfo; # getting the hash reference
print Dumper($var1);
...
...
}
1;
Can anyone please let me know, whether it is possible to replace the name of the hash-package (pack_hash), by using any variable, like:
my $pakVar = "pack_hash";
my $var1 = \%$pakVar::hashInfo;
I, know it is WRONG/NOT_CORRECT, but I want this kind of symbolic ref transformation, when I'm using strictures. I also wanted to know, whether it is possible to do the thing with eval. But I want a final variable, here $var1, 开发者_Go百科which will refer the particular hash (hashInfo);
No, that is not possible. But this is:
use strict;
use warnings;
use Symbol qw<qualify_to_ref>;
my $pakVar = 'pack_hash';
my $var1 = *{ qualify_to_ref( 'hashInfo', $pakVar ) }{HASH};
qualify_to_ref
takes the name of a package variable and the package name and returns a GLOB reference pointer, then you just access the HASH slot of the GLOB. You can also do it this way:
my $var1 = \%{ qualify_to_ref( 'hashInfo', $pakVar ) };
But it is just as easy to turn off strict
in a very tight do
as well;
my $var1
= do {
no strict;
\%{ $pakVar . '::hashInfo' };
};
I understand that some coding cultures consider turning off strict
or warnings
as "cheating". I know that I've had code review questions about turning off one class of warning in a small block like this. I knew which warnings I was going to get, so I didn't need it. The reviewer didn't see it this way.
For this reason some veteran Perl-ers think nothing about turning off strict. But if you can't because it makes the natives restless--you can use Symbol
. However, some shops have rules against package variables, so it never becomes an issue.
If you have a class method that returns a reference to the hash:
package pack_hash;
use strict;
use warnings;
our %hashInfo;
$hashInfo{abc} = ['a', 'b', 'c'];
sub hashInfo { \%hashInfo }
then you can easily get the reference:
use strict;
use warnings;
my $pakVar = 'pack_hash';
my $hashInfo = $pakVar->hashInfo();
print @{ $hashInfo->{'abc'} };
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