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Serialization and eval in YAML

by throop (Chaplain)
on Aug 13, 2012 at 16:30 UTC ( #987152=perlquestion: print w/replies, xml ) Need Help??
throop has asked for the wisdom of the Perl Monks concerning the following question:

Do I need to use eval when reading in a YAML file?

I'm used to serializing with Data::Dumper. It produces a dump string which, when loaded, sets variables to values. E.g:

use Data::Dumper; @arg2 = [{a => 1, b =>2}], [qw($balloon)]; Data::Dumper->Dump(@arg2)
'$balloon = { \'a\' => 1, \'b\' => 2 };
When that's printed to a file, and later loaded, $balloon gets set right. But for YAML:
use YAML::XS; @arg2 = ([{a => 1, b =>2}], [qw($balloon)]); Dump(@arg2)
'--- - a: 1 b: 2 --- - $balloon '
which, when loaded, gives,
0 ARRAY(0x89889e8) 0 HASH(0x8994130) 'a' => 1 'b' => 2 1 ARRAY(0x8ef27c8) 0 '$balloon'
Should I just use eval to get $balloon set to the right value? Or is there a YAML function to do this?

Replies are listed 'Best First'.
Re: Serialization and eval in YAML
by Anonymous Monk on Aug 13, 2012 at 17:15 UTC

    The YAML interface is nothing like Data::Dumper, use this instead

    my $string = Dump $oldbaloon; my $baloon = Load $string;

    Or the corresponding DumpFile/LoadFile

Re: Serialization and eval in YAML
by thundergnat (Deacon) on Aug 13, 2012 at 18:15 UTC
    use Data::Dumper;
    @arg2 = [{a => 1, b =>2}], [qw($balloon)];
    '$balloon = {
                 \'a\' => 1,
                 \'b\' => 2

    Really? Using no version of Perl that I've ever used.

    use warnings; use Data::Dumper; @arg2 = [{a => 1, b =>2}], [qw($balloon)]; print Data::Dumper->Dump(@arg2)
    Useless use of anonymous list ([]) in void context at line 3.
    $VAR1 = [
                'a' => 1,
                'b' => 2

    Precedence problem. You need parenthesis around the array. And lose the sigil on $balloon.

    Update: removed some unnecessarily snarky commentary.

      use Data::Dumper; print Data::Dumper->Dump( [{a => 1, b =>2}], [qw($balloon)] ); __END__ $balloon = { 'a' => 1, 'b' => 2 };

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Approved by lidden
[marto]: Does the command line arg --product-version@ help?
[LanX]: xD
[erix]: 'systematic' is going to be hard to define I think
[marto]: Err no @
LanX Much enemy much ore
[Corion]: marto: Naah, my module doesn't care, but the users of my module might expect some things to work in Chrome that only work in later builds (or, as seems to be the case, don't work there either ;) )
[Corion]: But I really wonder - I can tell Chrome to go offline, but requesting pages over the network still succeeds. But if I manually click the "offline" checkbox, that's different :-/

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