NAME
   Tie::SaveLater - A base class for tie modules that "save later".

SYNOPSIS
     package Tie::Storable;
     use base 'Tie::SaveLater';
     use Storable qw(retrieve nstore);
     __PACKAGE__->make_subclasses;
     sub load{ retrieve($_[1]) };
     sub save{ nstore($_[0], $_[0]->filename) };
     1;

     # later
     use Tie::Storable;
     {
         tie my $scalar => 'Tie::Storable', 'scalar.po';
         $scalar = 42;
     } # scalar is automatically saved as 'scalar.po'.
     {
         tie my @array => 'Tie::Storable', 'array.po';
         @array = qw(Sun Mon Tue Wed Fri Sat);
     } # array is automatically saved as 'array.po'.
     {
         tie my %hash => 'Tie::Storable', 'hash.po';
         %hash = (Sun=>0, Mon=>1, Tue=>2, Wed=>3, Thu=>4, Fri=>5, Sat=>6);
     } # hash is automatically saved as 'hash.po'.
     {
         tie my $object => 'Tie::Storable', 'object.po';
         $object = bless { First => 'Dan', Last => 'Kogai' }, 'DANKOGAI';
     } # You can save an object; just pass a scalar
     {
         tie my $object => 'Tie::Storable', 'object.po';
         $object->{WIFE} =  { First => 'Naomi', Last => 'Kogai' };
         # you can save before you untie like this
         tied($object)->save;
     }

DESCRIPTION
   Tie::SaveLater make you easy to write a modules that "save later", that
   is, save on untie.

 WHY?
   Today we have a number of serializers that store complex data
   structures, from Data::Dumper to Storable. If those core modules are not
   enough, you have YAML and DBI and more via CPAN.

   Problem? You have to save AFTER you are done with your data structure.
   Don't forget to save when you are out of scope just like locking the
   door before you leave.

   But can't you make it so it autosaves as Hotel doors autolocks? That's
   exactly what this module is for. This module comes with Tie::DataDumper,
   Tie::Storable, and Tie::YAML so you can make your data structures
   autosave today!

 DETAILS
   "SYNOPSIS" illustrates how to implement Tie::Storable in seven lines.
   Suppose your module is *Tie::Them*, Your module needs to do the
   following;

   * assign Tie::SaveLater as your base class

   * call __PACKAGE_->make_subclasses

     That automatically builds *Tie::Them::*SCALAR, *Tie::Them::*ARRAY, and
     *Tie::Them::*HASH for you.

   * define "load()" as a class method

     Here is a more descriptive way to define Tie::Storable::load().

        sub load{
          my $class    = shift;
          my $filename = shift;
          return retrieve($filename)
        };

     First argument is a class name (you don't need that in this case) and
     the second argument is the filename. It must return a loaded object.

   * define "save()" as an object method

     Here is a more descriptive way to define Tie::Storable::save().

       sub save{
           my $self = shift;
           my $filename = $self->filename;
           return nstore($self, $filename);
       };

     It takes only one argument -- $self. And you can obtain the filename
     as "$self->filename".

     You can also obtain optional arguments that are fed in "<tie"> as
     "$self->options" .

       tie my $obj, 'Tie::Them', 'them.obj', 0666, qw/more options/;

     In the statement above, "$self->options" returns (0666, 'more',
     'options'). This is handy you want to overload "FETCH()", "STORE()"
     and other tie methods for more minute control.

 EXPORT
   None by default.

SEE ALSO
   perltie, Tie::Scalar, Tie::Array, Tie::Hash

   Tie::Storable, Tie::YAML, Tie::DataDumper

AUTHOR
   Dan Kogai, <[email protected]>

COPYRIGHT AND LICENSE
   Copyright (C) 2006-2020 by Dan Kogai

   This library is free software; you can redistribute it and/or modify it
   under the same terms as Perl itself, either Perl version 5.8.8 or, at
   your option, any later version of Perl 5 you may have available.