in reply to How to get content of an XML::easytree output

G'day Tworec,

Welcome to the monastery.

Firstly, I see you've commented out "use strict;" - uncomment this and also add "use warnings;". Removing the output of warnings does not remove the problem they're telling you about!

You've commented out the declaration "my $element;". You assign nothing to $element. You then use $element as if it's a hashref - this is why you're getting the error message you report.

Your print_easy_tree() subroutine assigns its argument to $node; you then make no further reference to $node! Each instance of $element in this function should probably be $node.

I believe that should fix up your immediate problems. Here's some tips that you may find generally useful (i.e. not just for this code); the first two won't necessarily change how your code runs, but they should make it easier to read and understand:

-- Ken

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Re^2: How to get content of an XML::easytree output
by tobyink (Canon) on Mar 08, 2013 at 06:44 UTC

    "e.g. instead of print "<$element->{name}>";, use print '<', $element->{name}, '>';

    Personally, I'd prefer:

    printf '<%s>', $element->{name};

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    Update: just for the heck of it, this ain't too bad either:

    print "<$_>" for $element->{name};

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    Using postfix for to temporarily alias $_ is an idiom I don't see used very much, but is quite cute, and in this case has no speed penalty (quite the opposite in fact)...

    use strict;
use Benchmark ':all';

open $::dummy, ">", \$::data;

cmpthese(100_000, {
    print_for  => q[ $::data = ''; print {$::dummy} "<$_>" for "a" ],
    printf     => q[ $::data = ''; printf {$::dummy} "<%s>", "a" ],
});

__END__
             Rate    printf print_for
printf     7663/s        --      -79%
print_for 36765/s      380%        --

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    (PS: kcott's follow-up was posted before this update, so please don't read it as necessarily endorsing the for postfix technique.)

    package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name
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      That, too, is good; it isolates the $element->{name} (++).

      Tworec states "I am a perl newbie" and "<$element->{name}>" didn't seem to scream clarity; in particular, the <$element-> bit.

      -- Ken

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Re^2: How to get content of an XML::easytree output
by Tworec (Initiate) on Mar 08, 2013 at 08:52 UTC
    First of all, thanks for your reply. I changed all variables $element to $node and errors I reported are gone. But unfortunately a new one came. Not a HASH reference at line: if ($node->{type} eq 'e'). I think it's because of the $tree variable is ARRAY, but there is the main problem. My brain cannot really understand how to go threw an array of hashes and print it's elements. Should I write something like 
    if(ref($node) eq HASH) do the code I have
elsif(ref($node) eq ARRAY) $node = shift;

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    ?
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      Something like the following (untested) skeleton code: 

      sub print_easy_tree {
    my $node_array_ref = shift;

    for my $node (@$node_array_ref) {
        if ($node->{type} eq 'e') {
            ...
        }
        elsif ($node->{type} eq 't') {
            ...
        }
        else {
            ...
        }
    }
}

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      -- Ken

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        Great, it works now! Only if I could ask one more question.. Why @$ in @$node_array_ref? Why not just @?

        And if you know about a site where could I learn more of perl accessing to data, could you please give me a link? Of course I used google and found several sites with perl tutorials even in my language, but I mean if you know any you could personally recommend.

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