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920dae64 AT |
1 | package ODBM_File; |
2 | ||
3 | use strict; | |
4 | use warnings; | |
5 | ||
6 | require Tie::Hash; | |
7 | use XSLoader (); | |
8 | ||
9 | our @ISA = qw(Tie::Hash); | |
10 | our $VERSION = "1.06"; | |
11 | ||
12 | XSLoader::load 'ODBM_File', $VERSION; | |
13 | ||
14 | 1; | |
15 | ||
16 | __END__ | |
17 | ||
18 | =head1 NAME | |
19 | ||
20 | ODBM_File - Tied access to odbm files | |
21 | ||
22 | =head1 SYNOPSIS | |
23 | ||
24 | use Fcntl; # For O_RDWR, O_CREAT, etc. | |
25 | use ODBM_File; | |
26 | ||
27 | # Now read and change the hash | |
28 | $h{newkey} = newvalue; | |
29 | print $h{oldkey}; | |
30 | ... | |
31 | ||
32 | untie %h; | |
33 | ||
34 | =head1 DESCRIPTION | |
35 | ||
36 | C<ODBM_File> establishes a connection between a Perl hash variable and | |
37 | a file in ODBM_File format;. You can manipulate the data in the file | |
38 | just as if it were in a Perl hash, but when your program exits, the | |
39 | data will remain in the file, to be used the next time your program | |
40 | runs. | |
41 | ||
42 | Use C<ODBM_File> with the Perl built-in C<tie> function to establish | |
43 | the connection between the variable and the file. The arguments to | |
44 | C<tie> should be: | |
45 | ||
46 | =over 4 | |
47 | ||
48 | =item 1. | |
49 | ||
50 | The hash variable you want to tie. | |
51 | ||
52 | =item 2. | |
53 | ||
54 | The string C<"ODBM_File">. (Ths tells Perl to use the C<ODBM_File> | |
55 | package to perform the functions of the hash.) | |
56 | ||
57 | =item 3. | |
58 | ||
59 | The name of the file you want to tie to the hash. | |
60 | ||
61 | =item 4. | |
62 | ||
63 | Flags. Use one of: | |
64 | ||
65 | =over 2 | |
66 | ||
67 | =item C<O_RDONLY> | |
68 | ||
69 | Read-only access to the data in the file. | |
70 | ||
71 | =item C<O_WRONLY> | |
72 | ||
73 | Write-only access to the data in the file. | |
74 | ||
75 | =item C<O_RDWR> | |
76 | ||
77 | Both read and write access. | |
78 | ||
79 | =back | |
80 | ||
81 | If you want to create the file if it does not exist, add C<O_CREAT> to | |
82 | any of these, as in the example. If you omit C<O_CREAT> and the file | |
83 | does not already exist, the C<tie> call will fail. | |
84 | ||
85 | =item 5. | |
86 | ||
87 | The default permissions to use if a new file is created. The actual | |
88 | permissions will be modified by the user's umask, so you should | |
89 | probably use 0666 here. (See L<perlfunc/umask>.) | |
90 | ||
91 | =back | |
92 | ||
93 | =head1 DIAGNOSTICS | |
94 | ||
95 | On failure, the C<tie> call returns an undefined value and probably | |
96 | sets C<$!> to contain the reason the file could not be tied. | |
97 | ||
98 | =head2 C<odbm store returned -1, errno 22, key "..." at ...> | |
99 | ||
100 | This warning is emitted when you try to store a key or a value that | |
101 | is too long. It means that the change was not recorded in the | |
102 | database. See BUGS AND WARNINGS below. | |
103 | ||
104 | =head1 BUGS AND WARNINGS | |
105 | ||
106 | There are a number of limits on the size of the data that you can | |
107 | store in the ODBM file. The most important is that the length of a | |
108 | key, plus the length of its associated value, may not exceed 1008 | |
109 | bytes. | |
110 | ||
111 | See L<perlfunc/tie>, L<perldbmfilter>, L<Fcntl> | |
112 | ||
113 | =cut |