CODEWITHSUNDEEP
perlobjectmoose
mokko
mokko

Reputation: 186

Turn data structures into perl objects (module recommendation)

I have an arbitrary data structure and I'd like to treat it as an object. I get this as a response from a REST app. Example below. There are some modules on CPAN which promise to do this. Data::Object looks best to me, but it's last updated 2011. Am I missing something? Is there perhaps an easy Moose way to do this? Thanks!

$o=$class->new($response);
$s=$o->success;
@i=$o->items;
{
    'success' => bless( do{\(my $o = 1)}, 'JSON::XS::Boolean' ),
    'requestNumber' => 5,
    'itemsCount' => 1,
    'action' => 'search.json',
    'totalResults' => 161,
    'items' => [
        {
            'link' => 'http://europeana.eu/api//v2/record/15503/E627F23EF13FA8E6584AF8706A95DB85908413BE.json?wskey=NpXXXX',
            'provider' => [
                'Kulturpool'
            ],
            'europeanaCollectionName' => [
                '15503_Ag_AT_Kulturpool_khm_fs'
            ],
            # more fields omitted
        }
    ],
    'apikey' => 'Npxxxx'
};

Upvotes: 3

Views: 291

Answers (3)

David W.
David W.

Reputation: 107040

Although I don't like using it, defining an AUTOLOAD subroutine is a way to create arbitrary classes on the fly. It's been a while since I used it, but it should look something like this:

package Local::Foo;

sub new {
    my $class = shift;

    my $self = {};
    bless $self, $class;
    return $self;
}

sub AUTOLOAD {
    my $self = shift;
    my $value = shift;

    our $AUTOLOAD;
    (my $method = $AUTOLOAD) = s/.*:://;
    if ( defined $value ) {
        $self->{$method} = $value;
    }
    return $self->{$method};
}

This class Local::Foo has an infinite amount of methods. For example, if I said 

$foo->bar("fubar");

This would be the same as:

$foo->{bar} = "foobar";

If i called $foo->bar;, it will return the value of $foo->{bar};.

You probably want something to limit your method's style, and their values. For example, with this:

$foo->BAR;
$foo->Bar;
$foo->bar;

are all three valid and completely different methods. You probably want something to make sure your methods match a particular pattern (i.e., they're all lowercase, or the first letter is uppercase and the rest are lowercase. You probably want to make sure they start with a letter so, $foo->23diba; isn't a valid method.

One little problem: Once you define an AUTOLOAD subroutine, you also define DESTROY subroutine too. Perl calls the DESTROY subroutine before an object is destroyed. You need to handle the issue if $AUTOLOAD =~ /.*::DESTROY$/ too. You may need to add:

return if $AUTOLOAD =~ /.*::DESTROY$/;

somewhere in the AUTOLOAD subroutine, so you don't accidentally do something when DESTROY is called. Remember, it's automatically called whenever a class object falls out of scope if one exists, and with AUTOLOAD, you've defined one anyway.

Upvotes: 1

Ashley
Ashley

Reputation: 4335

I am not saying this is necessarily a good idea, the best way to do the idea, or gotcha-free. I never tried it till 15 minutes ago. But it is fun and it is terse, so–

#!/usr/bin/env perl
BEGIN {
    package Role::AutoVacca;
    use Moo::Role;
    use Scalar::Util "blessed";
    sub BUILD {
        my $self = shift;
        for my $attr ( grep /\A[^_]/, keys %{$self} )
        {
            Method::Generate::Accessor
                ->generate_method( blessed($self),
                                   $attr,
                                   { is => "rw" } );
        }
    }

    package Fakey;
    use Moo;
    with "Role::AutoVacca";
}

my $fake = Fakey->new({
    success => bless( do{\(my $o = 1)}, "JSON::XS::Boolean" ),
    items => [ { link => "http://europeana.eu/o/haipi",
                 provider => [ "mememememe" ] } ],
    apikey => "3k437" });

print "I CAN HAZ KEE? ", $fake->apikey, $/;
print "IZ GUD? ", $fake->success ? "YAH" : "ONOES", $/;
print "WUT DIZZYING? ", $fake->items, $/;

Upvotes: 0

Miguel Prz
Miguel Prz

Reputation: 13792

This is an example:

use strict;

package Foo; 

#define a simple Foo class with 3 properties
use base qw(Class::Accessor);
Foo->mk_accessors(qw(name role salary));


package main;
#define a perl hash with the same keys
my $hr = {'name'=>'john doe', 'role'=>'admin', 'salary'=>2500 };

#bless the object
my $obj = bless $hr, 'Foo';

print $obj->name, "\n"; #<-- prints: john doe

Upvotes: 0

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