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1 | package ODBM_File; |
2 | |
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3 | use strict; |
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4 | |
5 | require Tie::Hash; |
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6 | use XSLoader (); |
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7 | |
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8 | our @ISA = qw(Tie::Hash); |
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9 | our $VERSION = "1.03"; |
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10 | |
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11 | XSLoader::load 'ODBM_File', $VERSION; |
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12 | |
13 | 1; |
14 | |
15 | __END__ |
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16 | |
17 | =head1 NAME |
18 | |
19 | ODBM_File - Tied access to odbm files |
20 | |
21 | =head1 SYNOPSIS |
22 | |
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23 | use Fcntl; # For O_RDWR, O_CREAT, etc. |
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24 | use ODBM_File; |
25 | |
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26 | # Now read and change the hash |
27 | $h{newkey} = newvalue; |
28 | print $h{oldkey}; |
29 | ... |
30 | |
31 | untie %h; |
32 | |
33 | =head1 DESCRIPTION |
34 | |
35 | C<ODBM_File> establishes a connection between a Perl hash variable and |
36 | a file in ODBM_File format;. You can manipulate the data in the file |
37 | just as if it were in a Perl hash, but when your program exits, the |
38 | data will remain in the file, to be used the next time your program |
39 | runs. |
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40 | |
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41 | Use C<ODBM_File> with the Perl built-in C<tie> function to establish |
42 | the connection between the variable and the file. The arguments to |
43 | C<tie> should be: |
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44 | |
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45 | =over 4 |
46 | |
47 | =item 1. |
48 | |
49 | The hash variable you want to tie. |
50 | |
51 | =item 2. |
52 | |
53 | The string C<"ODBM_File">. (Ths tells Perl to use the C<ODBM_File> |
54 | package to perform the functions of the hash.) |
55 | |
56 | =item 3. |
57 | |
58 | The name of the file you want to tie to the hash. |
59 | |
60 | =item 4. |
61 | |
62 | Flags. Use one of: |
63 | |
64 | =over 2 |
65 | |
66 | =item C<O_RDONLY> |
67 | |
68 | Read-only access to the data in the file. |
69 | |
70 | =item C<O_WRONLY> |
71 | |
72 | Write-only access to the data in the file. |
73 | |
74 | =item C<O_RDWR> |
75 | |
76 | Both read and write access. |
77 | |
78 | =back |
79 | |
80 | If you want to create the file if it does not exist, add C<O_CREAT> to |
81 | any of these, as in the example. If you omit C<O_CREAT> and the file |
82 | does not already exist, the C<tie> call will fail. |
83 | |
84 | =item 5. |
85 | |
86 | The default permissions to use if a new file is created. The actual |
87 | permissions will be modified by the user's umask, so you should |
88 | probably use 0666 here. (See L<perlfunc/umask>.) |
89 | |
90 | =back |
91 | |
92 | =head1 DIAGNOSTICS |
93 | |
94 | On failure, the C<tie> call returns an undefined value and probably |
95 | sets C<$!> to contain the reason the file could not be tied. |
96 | |
97 | =head2 C<odbm store returned -1, errno 22, key "..." at ...> |
98 | |
99 | This warning is emmitted when you try to store a key or a value that |
100 | is too long. It means that the change was not recorded in the |
101 | database. See BUGS AND WARNINGS below. |
102 | |
103 | =head1 BUGS AND WARNINGS |
104 | |
105 | There are a number of limits on the size of the data that you can |
106 | store in the ODBM file. The most important is that the length of a |
107 | key, plus the length of its associated value, may not exceed 1008 |
108 | bytes. |
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109 | |
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110 | See L<perlfunc/tie>, L<perldbmfilter>, L<Fcntl> |
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111 | |
112 | =cut |