comment on

hmm, i thought about that and made up some code, just for fun.
i don't know if it's really useful and correct, but it was interesting to think about, so i'm just posting this here.
we're talking just about the object-attributes and the get/set methods, i assume.
so, when i create a class i usually find myself defining an attribute method like:

sub _attr {
  my $self = shift;
  my $name = shift;
  return $self->{"_$name"} unless @_;
  $self->{"_$name"} = shift;
}
sub name { shift->_attr(name => @_); }
[download]

so that you can call $obj->name("new name");
(I know i could actually use Class::MethodMaker or something similar...)

now how could we make that more generic?
i thought about defining a pragma 'attribute' that you can use like that:

package Parent;
use attribute sub {
  my $self = shift;
  my $name = shift;
  # we have an ordinary hashref for the object
  return \$self->{"_$name"};
}, [qw(city name)];
[download]

package Child;
use base 'Parent';
use attribute sub {
  my $self = shift;
  my $name = shift;
  # object is arrayref, and the attributes are stored in element 0
  return \$self->[0]->{"_$name"};
};
[download]

so with that, and the assumption that the module you inherit always uses methods to get/set attributes, you are independent from the implementation, right? here's attribute.pm:

package attribute;
use strict;
use warnings;
sub import {
  my ($self, $sub, $names) = @_;
  my $class = caller();
  no strict 'refs';
  # set the general method
  *{$class . '::_attribute_ref' } = $sub;
  for my $name (@$names) {
    my $string = $class . '::' . $name;
    *{$string} = sub {
      my $self = shift;
      # set method for each attribute
      return ${ $self->_attribute_ref($name) } unless @_;
      ${ $self->_attribute_ref($name) } = shift;
    };
  }
}
1;
[download]

update: changed subname '_attribute_set' to '_attribute_ref'
moved readmore tag a little

In reply to Re: Why is a hash the default "object" in oo perl? by tinita
in thread Why is a hash the default "object" in oo perl? by theAcolyte

Are you posting in the right place? Check out Where do I post X? to know for sure.
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
Want more info? How to link or How to display code and escape characters are good places to start.


We don't bite newbies here... much
	PerlMonks