Perl Hacks

Hack #50. Autogenerate Your Accessors

Stop writing accessor methods by hand.

One of the Perl virtues is laziness. This doesn't mean not doing your work, it means doing your work with as little effort as possible. When you find yourself typing the same code over and over again, stop! Make the computer do the work.

Method accessors/mutators (getters/setters) are a case in point. Here's a simple object-oriented module:

package My::Customer;

use strict;
use warnings;

sub new { bless { }, shift }

sub first_name
{
    my $self            = shift;
    return $self->{first_name} unless @_;
    $self->{first_name} = shift;
    return $self;
}

sub last_name
{
    my $self           = shift;
    return $self->{last_name} unless @_;
    $self->{last_name} = shift;
    return $self;
}

sub full_name
{
    my $self = shift;
    return join ' ', $self->first_name( ), $self->last_name( );
}

1;

and a small program to use it:

my $cust = My::Customer->new( );
$cust->first_name( 'John' );
$cust->last_name( 'Public' );
print $cust->full_name( );

That prints John Public.

Of course, if this is really is a customer object, it needs to do more. You might need to set a customer's credit rating, the identity of a primary salesperson, and so on.

As you can see, the first_name and last_name methods are effectively duplicates of one another. New accessors are likely to be the very similar. Can you automate this?

The Hack

There are many modules on the CPAN which handle this, all in slightly different flavors. Here are two—one of the most widespread and one of the least constraining. ...