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1 | package ODBM_File; |
2 | |
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3 | use strict; |
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4 | use warnings; |
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5 | |
6 | require Tie::Hash; |
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7 | use XSLoader (); |
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8 | |
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9 | our @ISA = qw(Tie::Hash); |
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10 | our $VERSION = "1.06"; |
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11 | |
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12 | XSLoader::load 'ODBM_File', $VERSION; |
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13 | |
14 | 1; |
15 | |
16 | __END__ |
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17 | |
18 | =head1 NAME |
19 | |
20 | ODBM_File - Tied access to odbm files |
21 | |
22 | =head1 SYNOPSIS |
23 | |
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24 | use Fcntl; # For O_RDWR, O_CREAT, etc. |
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25 | use ODBM_File; |
26 | |
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27 | # Now read and change the hash |
28 | $h{newkey} = newvalue; |
29 | print $h{oldkey}; |
30 | ... |
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31 | |
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32 | untie %h; |
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33 | |
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34 | =head1 DESCRIPTION |
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35 | |
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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. |
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41 | |
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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: |
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45 | |
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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 | |
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100 | This warning is emitted when you try to store a key or a value that |
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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. |
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110 | |
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111 | See L<perlfunc/tie>, L<perldbmfilter>, L<Fcntl> |
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112 | |
113 | =cut |