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'
$self->slot2; #returns 'value2'
DESCRIPTION
Package::Base is an abstract base class, meaning it isn't intended to be
used directly, but rather inherited from by an instantiable class. In
fact, attempting to instantiate a Package::Base object directly will
result in an error.
Q: So why would you want to inherit from Package::Base?
A: Because it provides some nice functionality:
* a built-in new() method that does instantiation of a hash based object
* new() accepts an anonymous hash as arguments (a list of key/value
pairs, essentially). and sets attributes appropriately within your
object if methods of the same name as the keys are found.
* Package::Base::Devel is a subclass specifically designed for debugging
Perl classes is bundled with Package::Base, and the inherited interface
works the same way. This means that while developing/debugging a module,
you can do:
package My::Package;
use base qw(Package::Base::Devel);
#...
and have nice Log::Log4perl logging about what your method is doing sent
to a file, filehandle, email, database... whatever (see Log::Log4perl
for details about this amazing logging API). Then, when you're ready to
ship, just change the line:
package My::Package;
-use base qw(Package::Base::Devel);
+use base qw(Package::Base);
and the heavy debugging toll paid for the debug logging vanishes.
* Package::Base comes with a pstub, a drop-in replacement for h2xs if
you're writing a module that doesn't rely on Perl XS or C files.
Now to be "fair and balanced" :)
Q: Why might Package::Base not be right for me?
A: It does some things you might not like for stylistic reasons:
* Package::Base currently only works for hash-based objects. This may be
extended to support array-based objects in the future.
* Package::Base assumes you have methods overloaded to act as
accessors/mutators. e.g. calling "$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, <
[email protected]>
SEE ALSO
For another way to do it, see Class::Base,
Class::Accessor.
