Re: Using a factory class to return objects of the same class

Your question is too abstract. The Factory Method Pattern is usually used to create objects of different classes. If the resulting object is always of the same class, just built in a different way, you rather want a Builder.

You can have a Factory of Builders, but I fear I used too much imagination so the following might not be usable for your situation. It also doesn't make any sense for the simple situation I created, but that's how OO programming works - without particular objects and behaviours, it's all hand waving. It's hard to abstract from something that's already been abstracted.

#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

{   package MyClass;
    use Moo;

    has [qw[ id name data ]] => (is => 'ro', required => 1);

    sub job { my ($self) = @_; $self->data->{ $self->id } }
}

{   package MyClass::Builder::FromElements;
    use Moo;

    has root => (is => 'ro');

    sub build {
        my ($self, %data) = @_;
        return 'MyClass'->new(data => \%data,
                              map +($_ => $self->root->findvalue("/r/$
+_")),
                                  qw( id name ))
    }
}

{   package MyClass::Builder::FromAttributes;
    use Moo;

    has root => (is => 'ro');

    sub build {
        my ($self, %data) = @_;
        return 'MyClass'->new(data => \%data,
                              map +($_ => $self->root->findvalue("/r/\
+@$_")),
                                  qw( id name ))
    }
}

{   package MyClass::Builder::Factory;
    use Moo;
    use XML::LibXML;

    has xml => (is => 'ro');
    has _root => (is => 'lazy', init_arg => undef);

    sub build_builder {
        my ($self) = @_;
        if (2 == $self->_root->findvalue('count(/r/id | /r/name)')) {
            return MyClass::Builder::FromElements->new(root => $self->
+_root)

        } elsif (2 == $self->_root->findvalue('count(/r/@id | /r/@name
+)')) {
            return MyClass::Builder::FromAttributes->new(root => $self
+->_root)

        } else {
            die "Can't build.\n";
        }
    }

    sub _build__root {
        my ($self) = @_;
        return 'XML::LibXML'->load_xml(string => $self->xml)->document
+Element
    }
}

my %DATA = (12 => 'CEO', 14 => 'CTO');

for my $xml (
    '<r><id>12</id><name>John</name></r>',
    '<r id="14" name="Jane"/>'
) {
    my $builder = 'MyClass::Builder::Factory'->new(xml => $xml)->build
+_builder;
    my $o = $builder->build(%DATA);
    say join ', ', map $o->$_, qw( id name job );
}
[download]

map{substr$_->[0],$_->[1]||0,1}[\*||{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^*ARGV,3]

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Re^2: Using a factory class to return objects of the same class by Amblikai (Scribe) on May 21, 2019 at 16:59 UTC
If i was using a builder method(s) to handle the configuration of the object, how would i go about seperating the configuration from the incoming data (since the data is somewhat arbitrary)? I'm thinking of just using class methods/variables to set up the configuration of the class before creating objects	[reply]
Re^3: Using a factory class to return objects of the same class by choroba (Cardinal) on May 21, 2019 at 18:53 UTC
Builder is not a method, it's an object. Its constructor takes the configuration, and its `->build` method takes the data as an argument. `map{substr$_->[0],$_->[1]\|\|0,1}[\\|\|{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^ARGV,3]`	[reply] [d/l] [select]