NAME

Package::Base - An abstract base for implementation classes to inherit from

SYNOPSIS

      #don't use this module directly, but rather inherit from it.
      package My::Package;
      use base qw(Package::Base);

      #define a couple of get/setters
      sub slot1 {
        my($self,$val) = @_;
        $self->{'slot1'} = $val if defined($val);
        return $self->{'slot1'};
      }

      sub slot2 {
        my($self,$val) = @_;
        $self->{'slot2'} = $val if defined($val);
        return $self->{'slot2'};
      }

      package main:
      my $object = My::Package->new(slot1 => 'value1', slot2 => 'value2', slot3 => 'value3');
      #slot3 => 'value3' is silently ignored

      $self->slot1; #returns 'value1'
      $self->slot2; #returns 'value2'

DESCRIPTION

Package::Base is an abstract base class, meaning it isn't intended to be used directly, but rather inherited from by an instantiable class. In fact, attempting to instantiate a Package::Base object directly will result in an error.

Q: So why would you want to inherit from Package::Base?

1. Because it provides some nice functionality:
   • a built-in new() method that does instantiation of a hash based object
   • new() accepts an anonymous hash as arguments (a list of key/value pairs, essentially). and sets attributes appropriately within your object if methods of the same name as the keys are found.
   • Package::Base::Devel is a subclass specifically designed for debugging Perl classes is bundled with Package::Base, and the inherited interface works the same way. This means that while developing/debugging a module, you can do:

     package My::Package; use base qw(Package::Base::Devel);

     #...

and have nice Log::Log4perl logging about what your method is doing sent to a file, filehandle, email, database... whatever (see Log::Log4perl for details about this amazing logging API). Then, when you're ready to ship, just change the line:

      package My::Package;
      -use base qw(Package::Base::Devel);
      +use base qw(Package::Base);

and the heavy debugging toll paid for the debug logging vanishes.

• Package::Base comes with a pstub, a drop-in replacement for h2xs if you're writing a module that doesn't rely on Perl XS or C files.

Now to be "fair and balanced" :)

Q: Why might Package::Base not be right for me?

1. It does some things you might not like for stylistic reasons:
   • Package::Base currently only works for hash-based objects. This may be extended to support array-based objects in the future.
   • Package::Base assumes you have methods overloaded to act as accessors/mutators. e.g. calling "$obj-"foo(1)> sets object's foo attribute to 1, and calling "$obj-"foo()> retrieves object's foo attribute's value. See Class::Accessor for an easy way to set these up.
   • Package::Base tries to initialize slots for all passed key/value pairs, instead of allowing the constructor, new(), to filter out only those it wants. Class::Base allows filtering like this.

AUTHOR

Allen Day, <allenday@ucla.edu>

SEE ALSO

For another way to do it, see Class::Base, Class::Accessor.