[perl5.git] / ext / ODBM_File / ODBM_File.pm

package ODBM_File;

use strict;
use warnings;

require Tie::Hash;
use XSLoader ();

our @ISA = qw(Tie::Hash);
our $VERSION = "1.03";

XSLoader::load 'ODBM_File', $VERSION;

1;

__END__

=head1 NAME

ODBM_File - Tied access to odbm files

=head1 SYNOPSIS

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

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

  untie %h;

=head1 DESCRIPTION

C<ODBM_File> establishes a connection between a Perl hash variable and
a file in ODBM_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<ODBM_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<"ODBM_File">.  (Ths tells Perl to use the C<ODBM_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<odbm 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 ODBM 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
Commit	Line	Data
a0d0e21e LW	1	package ODBM_File;
a0d0e21e LW	2
96318ac8	3	use strict;
698828ad	4	use warnings;
96318ac8 PM	5
96318ac8 PM	6	require Tie::Hash;
ef7f72ff	7	use XSLoader ();
a0d0e21e	8
17f410f9	9	our @ISA = qw(Tie::Hash);
cbc5248d	10	our $VERSION = "1.03";
c07a80fd	11
9426adcd	12	XSLoader::load 'ODBM_File', $VERSION;
a0d0e21e LW	13
	14	1;
	15
	16	__END__
a5f75d66 AD	17
	18	=head1 NAME
	19
	20	ODBM_File - Tied access to odbm files
	21
	22	=head1 SYNOPSIS
	23
0fbd2a46	24	use Fcntl; # For O_RDWR, O_CREAT, etc.
a5f75d66 AD	25	use ODBM_File;
a5f75d66 AD	26
0fbd2a46 JH	27	# Now read and change the hash
	28	$h{newkey} = newvalue;
	29	print $h{oldkey};
	30	...
bbc7dcd2	31
0fbd2a46	32	untie %h;
bbc7dcd2	33
0fbd2a46	34	=head1 DESCRIPTION
bbc7dcd2	35
0fbd2a46 JH	36	C<ODBM_File> establishes a connection between a Perl hash variable and
	37	a file in ODBM_File format;. You can manipulate the data in the file
	38	just as if it were in a Perl hash, but when your program exits, the
	39	data will remain in the file, to be used the next time your program
	40	runs.
a5f75d66	41
0fbd2a46 JH	42	Use C<ODBM_File> with the Perl built-in C<tie> function to establish
	43	the connection between the variable and the file. The arguments to
	44	C<tie> should be:
a5f75d66	45
0fbd2a46 JH	46	=over 4
	47
	48	=item 1.
	49
	50	The hash variable you want to tie.
	51
	52	=item 2.
	53
	54	The string C<"ODBM_File">. (Ths tells Perl to use the C<ODBM_File>
	55	package to perform the functions of the hash.)
	56
	57	=item 3.
	58
	59	The name of the file you want to tie to the hash.
	60
	61	=item 4.
	62
	63	Flags. Use one of:
	64
	65	=over 2
	66
	67	=item C<O_RDONLY>
	68
	69	Read-only access to the data in the file.
	70
	71	=item C<O_WRONLY>
	72
	73	Write-only access to the data in the file.
	74
	75	=item C<O_RDWR>
	76
	77	Both read and write access.
	78
	79	=back
	80
	81	If you want to create the file if it does not exist, add C<O_CREAT> to
	82	any of these, as in the example. If you omit C<O_CREAT> and the file
	83	does not already exist, the C<tie> call will fail.
	84
	85	=item 5.
	86
	87	The default permissions to use if a new file is created. The actual
	88	permissions will be modified by the user's umask, so you should
	89	probably use 0666 here. (See L<perlfunc/umask>.)
	90
	91	=back
	92
	93	=head1 DIAGNOSTICS
	94
	95	On failure, the C<tie> call returns an undefined value and probably
	96	sets C<$!> 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 emmitted 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.
a5f75d66	110
0fbd2a46	111	See L<perlfunc/tie>, L<perldbmfilter>, L<Fcntl>
a5f75d66 AD	112
a5f75d66 AD	113	=cut