Re: unblessed reference problem

Step through each key you pass in, and recurse into each hash with that key, like this (but not so ad-hoc and ugly):

#!/usr/bin/perl
use strict; use warnings;
use Data::Dumper;

my $arr = 
    { a => 
          { b => 'c', 
            d => 
                { e => 
                      { x => 'y', 
                        k => [ 'A'...'Z'],
                      }
                } ,
           }, 
           f => 
                { g => 'h', 
                  i => 'm' 
                }
     };
sub arr_parse {
    my $data = shift;
    my @params = @_;
    my $newdata = $data;
    foreach my $parm (@params) {
        if (ref $newdata eq 'ARRAY') {
            $newdata = $newdata->[$parm] 
        } elsif (ref $newdata eq 'HASH') {
            $newdata = $newdata->{$parm}
        } else {
            last
        }
    }
    return $newdata
}

my $retval = arr_parse( $arr, qw{a d e x} );
print Dumper( $retval ) . "\n";
my $retval2 = arr_parse( $arr, qw{a d e k 15} );
print Dumper( $retval2 ) . "\n";
[download]

EDIT: Updated to deal with hashes and arrays.

Comment on Re: unblessed reference problem Download Code

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Re^2: unblessed reference problem by gdolph (Novice) on Mar 26, 2010 at 11:51 UTC
Thanks james2vegas, that is definitely a very good solution to this specific problem. What I really want to know is how to get perl to do what I originally posted. I'm well aware some of the more esoteric solutions might be dangerous, but I still want to know how it works to further my knowledge.	[reply]
Re^3: unblessed reference problem by almut (Canon) on Mar 26, 2010 at 12:12 UTC
but I still want to know how it works If you're referring to the `eval` thing, that would be: `#!/usr/bin/perl -l use strict; use warnings; my $hash = { domain => { foo => { bar => "baz" } } }; my $domain = "domain"; my $var1 = "foo"; my $var2 = "bar"; my $test = '{$var1}{$var2}'; my $value = eval '$hash->{$domain}'.$test; print $value; # "baz"` [download] That said, better stay away from `eval` unless you know what you're doing, because it's potentially dangerous when you overlook something (e.g. when the value of `$test` might originate from somewhere not under your full control) code using it is unnecessarily hard to read and maintain it's unnecessarily slow	[reply] [d/l] [select]
Re^4: unblessed reference problem by gdolph (Novice) on Mar 26, 2010 at 12:22 UTC
That's excellent stuff, thanks almut! Just what I needed to know.	[reply]
Re^3: unblessed reference problem by Anonymous Monk on Mar 26, 2010 at 11:55 UTC
sigh To make `$hash->{$domain}$test;` into `$hash->{$domain}{$var1}{$var2}` you have to write `$foo` such that `print $foo` prints `$hash->{$domain}{$var1}{$var2}`, then you can `eval $foo` to execute.	[reply] [d/l] [select]