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lib/Class/Null.pm  view on Meta::CPAN

  # some class constructor and accessor declaration here

  sub init {
    my $self = shift;
    ...
    $self->log(Class::Null->new);
    ...
  }

  sub do_it {
    my $self = shift;
    $self->log->log(level => 'debug', message => 'starting to do it');
    ...
    $self->log->log(level => 'debug', message => 'still doing it');
    ...
    $self->log->log(level => 'debug', message => 'finished doing it');
  }

This is only one example of using a null class, but it can be used whenever
you want to make an optional helper object into a mandatory helper object,
thereby avoiding unnecessarily complicated checks and preserving the
transparency of how your objects are related to each other and how they
call each other.

Although C<Class::Null> is exceedingly simple it has been made into a
distribution and put on CPAN to avoid further clutter and repetitive
definitions.

=head1 METHODS

=head2 new

Returns the singleton null object.

=head2 Any other method

Returns another singleton null object so method chaining works.

=head1 OVERLOADS

=over 4

=item Boolean context

In boolean context, a null object always evaluates to false.

=item Numeric context

When used as a number, a null object always evaluates to 0.

=item String context

When stringified, a null object always evaluates to the empty string.

=back

=head1 INSTALLATION

See perlmodinstall for information and options on installing Perl modules.

=head1 BUGS AND LIMITATIONS

No bugs have been reported.

Please report any bugs or feature requests through the web interface at
L<http://rt.cpan.org/Public/Dist/Display.html?Name=Class-Null>.

=head1 AVAILABILITY

The latest version of this module is available from the Comprehensive Perl
Archive Network (CPAN). Visit L<http://www.perl.com/CPAN/> to find a CPAN
site near you, or see L<http://search.cpan.org/dist/Class-Null/>.

The development version lives at L<http://github.com/hanekomu/Class-Null>
and may be cloned from L<git://github.com/hanekomu/Class-Null.git>.
Instead of sending patches, please fork this project using the standard
git and github infrastructure.

=head1 AUTHOR

Marcel Gruenauer <marcel@cpan.org>

=head1 COPYRIGHT AND LICENSE

This software is copyright (c) 2005 by Marcel Gruenauer.

This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.

=cut