SPUG:Object property question

[Sanford Morton]

Here's one example, if I understand you correctly. Of course if this is a
database, you'll also need module routines to read to and write from the
database at the appropriate times, including the id number of the last member
created. I haven't tested any of this.


### code inside Member.pm        ### code inside script 

package Member;		         use Member;              
use strict;		         my $m = Member->new('Jane', 'Doe');
			         print $m->id(); 
my $_lastid = 0; # class vble      ==> prints id number
                                 print $m->firstname('Mary');
sub new {        # constructor     ==> changes and prints first name
    my $class = shift;
    my $self = {};
    $self->_init(@_);
    return bless $self, $class;
}

sub _init {      # initialization, private
    my $self = shift;  
    $self->{'_firstname'} = $_[0];
    $self->{'_lastname'} = $_[1];
    $self->{'_id'} = ++$lastid;
}

sub firstname {  # accessor, public
    my $self = shift;  
    $self->{'_firstname'} = $_[0] if @_;
    return $self->{'_firstname'};
}

sub id {         # accessor, public
    my $self = shift;  
    return $self->{'_id'};
}


I find it useful in module code to prefix with an underscore all internal
variables and functions (that aren't documented in the public interface and
aren't intended to be used by the user). If you're starved for another
introductory Perl object tutorial, you can scan the one at

  http://www.speakeasy.org/~cgires/modules/

Or, for books, Damian Conway's is my favorite.