Factories are usually used by objects to create child objects. The purpose of the factory is to avoid having to hardcode a class name. For example, 
package Tree;

sub add_item {
   my ($self, $item) = @_;
   my $parent_node = ...;
   $parent_node->add(new Node($item));
}

[download]

would be transfored into the following when using a factory: 

package Tree;

sub add_item {
   my ($self, $item) = @_;
   my $node_factory = $self->{node_factory};
   my $parent_node = ...;
   $parent_node->add($node_factory->create($item));
}

sub set_node_factory {
   my ($self, $node_factory) = @_;
   $self->{node_factory} = $node_factory;
}

package NodeFactory;

# Overridable
sub create {
   shift(@_);
   return Node->new(@_);
}

[download]

But that's pretty useless in Perl, since it lacks the typing of Java. In Perl, you could easily accept a class name (e.g. 'Node') or a code ref (e.g. sub { Node->new(@_) }) instead of a factory.

In reply to Re: Do I need a Factory Class At This Point? by ikegami
in thread Do I need a Factory Class At This Point? by jffry

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.