Package Tie::Hash::SaveConfig;

use strict;
use vars qw(@ISA);

@ISA = qw(Tie::StdHash);

sub TIEHASH {
 my $class = shift;
 my %hash;
 bless \%hash,$class;
}

sub STORE {
  my ($self,$key,$value) = @_;
  $self->SaveConfig($key,$value,$self->{$key});
  $self->{$key} = $value; #Redefine value
  return $value;
}

sub DELETE {
  my ($self,$key) = @_;
  $self->SaveConfig($key,$self->{$key});
  return $self->{$key};
}  

sub SaveConfig {
  my $self = shift @_;
  #Do something here
}

}

1;
__END__
[download]

use Tie::Hash::SaveConfig;
my %hash = ();
tie %hash,'Tie::Hash::SaveConfig';
%hash = (Foo=>"Bar");
[download]

Good answer, Beatnik! Allow me to suggest a simplification to your solution. Use SUPER;) and you don't need the TIEHASH routine.

Package Tie::Hash::SaveConfig;
@ISA = qw(Tie::StdHash);

use strict;
sub STORE {
    my $self = shift;
    SaveConfig();
    $self->SUPER::STORE(@_);
    # or (probably better) here:
    # SaveConfig();
}
 
sub SaveConfig {
    # do something ...
    print "Config saved\n";
}

1;
[download]

Update: Note merlyn's comment below. I put an additional comment into the code. From the original post, though, it's not clear what is actually wanted.

-- Hofmator

    SaveConfig(); 
    $self->SUPER::STORE(@_);
[download]

I'd swap those two lines: that way the hash is in the new state before the config is saved, unless the point was to save the old config.

-- Randal L. Schwartz, Perl hacker

Well I didn't really know what he wanted :) but a ++ ! :)

Greetz
Beatnik
... Quidquid perl dictum sit, altum viditur.