1package Memoize::NDBM_File;
2
3=head1 NAME
4
5Memoize::NDBM_File - glue to provide EXISTS for NDBM_File for Storable use
6
7=head1 DESCRIPTION
8
9See L<Memoize>.
10
11=cut
12
13use NDBM_File;
14@ISA = qw(NDBM_File);
15$VERSION = 0.65;
16
17$Verbose = 0;
18
19sub AUTOLOAD {
20  warn "Nonexistent function $AUTOLOAD invoked in Memoize::NDBM_File\n";
21}
22
23sub import {
24  warn "Importing Memoize::NDBM_File\n" if $Verbose;
25}
26
27
28my %keylist;
29
30# This is so ridiculous...
31sub _backhash {
32  my $self = shift;
33  my %fakehash;
34  my $k;
35  for ($k = $self->FIRSTKEY(); defined $k; $k = $self->NEXTKEY($k)) {
36    $fakehash{$k} = undef;
37  }
38  $keylist{$self} = \%fakehash;
39}
40
41sub EXISTS {
42  warn "Memoize::NDBM_File EXISTS (@_)\n" if $Verbose;
43  my $self = shift;
44  _backhash($self)  unless exists $keylist{$self};
45  my $r = exists $keylist{$self}{$_[0]};
46  warn "Memoize::NDBM_File EXISTS (@_) ==> $r\n" if $Verbose;
47  $r;
48}
49
50sub DEFINED {
51  warn "Memoize::NDBM_File DEFINED (@_)\n" if $Verbose;
52  my $self = shift;
53  _backhash($self)  unless exists $keylist{$self};
54  defined $keylist{$self}{$_[0]};
55}
56
57sub DESTROY {
58  warn "Memoize::NDBM_File DESTROY (@_)\n" if $Verbose;
59  my $self = shift;
60  delete $keylist{$self};   # So much for reference counting...
61  $self->SUPER::DESTROY(@_);
62}
63
64# Maybe establish the keylist at TIEHASH time instead?
65
66sub STORE {
67  warn "Memoize::NDBM_File STORE (@_)\n" if $VERBOSE;
68  my $self = shift;
69  $keylist{$self}{$_[0]} = undef;
70  $self->SUPER::STORE(@_);
71}
72
73
74
75# Inherit FETCH and TIEHASH
76
771;
78