ext/SDBM_File/SDBM_File.pm

package SDBM_File;

use strict;
use warnings;

require Tie::Hash;
use XSLoader ();

our @ISA = qw(Tie::Hash);
our $VERSION = "1.04" ;

XSLoader::load 'SDBM_File', $VERSION;

1;

__END__

=head1 NAME

SDBM_File - Tied access to sdbm files

=head1 SYNOPSIS

 use Fcntl;   # For O_RDWR, O_CREAT, etc.
 use SDBM_File;

 tie(%h, 'SDBM_File', 'filename', O_RDWR|O_CREAT, 0666)
   or die "Couldn't tie SDBM file 'filename': $!; aborting";

 # Now read and change the hash
 $h{newkey} = newvalue;
 print $h{oldkey}; 
 ...

 untie %h;

=head1 DESCRIPTION

C<SDBM_File> establishes a connection between a Perl hash variable and
a file in SDBM_File format;.  You can manipulate the data in the file
just as if it were in a Perl hash, but when your program exits, the
data will remain in the file, to be used the next time your program
runs.

Use C<SDBM_File> with the Perl built-in C<tie> function to establish
the connection between the variable and the file.  The arguments to
C<tie> should be:

=over 4

=item 1.

The hash variable you want to tie.

=item 2. 

The string C<"SDBM_File">.  (Ths tells Perl to use the C<SDBM_File>
package to perform the functions of the hash.)

=item 3. 

The name of the file you want to tie to the hash.  

=item 4.

Flags.  Use one of:

=over 2

=item C<O_RDONLY>

Read-only access to the data in the file.

=item C<O_WRONLY>

Write-only access to the data in the file.

=item C<O_RDWR>

Both read and write access.

=back

If you want to create the file if it does not exist, add C<O_CREAT> to
any of these, as in the example.  If you omit C<O_CREAT> and the file
does not already exist, the C<tie> call will fail.

=item 5.

The default permissions to use if a new file is created.  The actual
permissions will be modified by the user's umask, so you should
probably use 0666 here. (See L<perlfunc/umask>.)

=back

=head1 DIAGNOSTICS

On failure, the C<tie> call returns an undefined value and probably
sets C<$!> to contain the reason the file could not be tied.

=head2 C<sdbm store returned -1, errno 22, key "..." at ...>

This warning is emmitted when you try to store a key or a value that
is too long.  It means that the change was not recorded in the
database.  See BUGS AND WARNINGS below.

=head1 BUGS AND WARNINGS

There are a number of limits on the size of the data that you can
store in the SDBM file.  The most important is that the length of a
key, plus the length of its associated value, may not exceed 1008
bytes.

See L<perlfunc/tie>, L<perldbmfilter>, L<Fcntl>

=cut
Revision:	1.1
Committed:	Thu Jun 30 14:27:04 2005 UTC (21 years, 3 months ago) by root
Branch:	MAIN
CVS Tags:	PERL-5-8-7, HEAD
Branch point for:	PERL
Log Message:	* empty log message *
#	User	Rev	Content
1	root	1.1	package SDBM_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 = "1.04" ;
11
12			XSLoader::load 'SDBM_File', $VERSION;
13
14			1;
15
16			__END__
17
18			=head1 NAME
19
20			SDBM_File - Tied access to sdbm files
21
22			=head1 SYNOPSIS
23
24			use Fcntl; # For O_RDWR, O_CREAT, etc.
25			use SDBM_File;
26
27			tie(%h, 'SDBM_File', 'filename', O_RDWR\|O_CREAT, 0666)
28			or die "Couldn't tie SDBM file 'filename': $!; aborting";
29
30			# Now read and change the hash
31			$h{newkey} = newvalue;
32			print $h{oldkey};
33			...
34
35			untie %h;
36
37			=head1 DESCRIPTION
38
39			C<SDBM_File> establishes a connection between a Perl hash variable and
40			a file in SDBM_File format;. You can manipulate the data in the file
41			just as if it were in a Perl hash, but when your program exits, the
42			data will remain in the file, to be used the next time your program
43			runs.
44
45			Use C<SDBM_File> with the Perl built-in C<tie> function to establish
46			the connection between the variable and the file. The arguments to
47			C<tie> should be:
48
49			=over 4
50
51			=item 1.
52
53			The hash variable you want to tie.
54
55			=item 2.
56
57			The string C<"SDBM_File">. (Ths tells Perl to use the C<SDBM_File>
58			package to perform the functions of the hash.)
59
60			=item 3.
61
62			The name of the file you want to tie to the hash.
63
64			=item 4.
65
66			Flags. Use one of:
67
68			=over 2
69
70			=item C<O_RDONLY>
71
72			Read-only access to the data in the file.
73
74			=item C<O_WRONLY>
75
76			Write-only access to the data in the file.
77
78			=item C<O_RDWR>
79
80			Both read and write access.
81
82			=back
83
84			If you want to create the file if it does not exist, add C<O_CREAT> to
85			any of these, as in the example. If you omit C<O_CREAT> and the file
86			does not already exist, the C<tie> call will fail.
87
88			=item 5.
89
90			The default permissions to use if a new file is created. The actual
91			permissions will be modified by the user's umask, so you should
92			probably use 0666 here. (See L<perlfunc/umask>.)
93
94			=back
95
96			=head1 DIAGNOSTICS
97
98			On failure, the C<tie> call returns an undefined value and probably
99			sets C<$!> to contain the reason the file could not be tied.
100
101			=head2 C<sdbm store returned -1, errno 22, key "..." at ...>
102
103			This warning is emmitted when you try to store a key or a value that
104			is too long. It means that the change was not recorded in the
105			database. See BUGS AND WARNINGS below.
106
107			=head1 BUGS AND WARNINGS
108
109			There are a number of limits on the size of the data that you can
110			store in the SDBM file. The most important is that the length of a
111			key, plus the length of its associated value, may not exceed 1008
112			bytes.
113
114			See L<perlfunc/tie>, L<perldbmfilter>, L<Fcntl>
115
116			=cut