[p5sagit/p5-mst-13.2.git] / ext / NDBM_File / NDBM_File.pm

package NDBM_File;

BEGIN {
    if ($] >= 5.002) {
	use strict;
    }
}

require Tie::Hash;
use XSLoader ();

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

XSLoader::load 'NDBM_File', $VERSION;

1;

__END__

=head1 NAME

NDBM_File - Tied access to ndbm files

=head1 SYNOPSIS

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

  # Now read and change the hash
  $h{newkey} = newvalue;
  print $h{oldkey}; 
  ...
 
  untie %h;
 
=head1 DESCRIPTION
 
C<NDBM_File> establishes a connection between a Perl hash variable and
a file in NDBM_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<NDBM_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<"NDBM_File">.  (Ths tells Perl to use the C<NDBM_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<ndbm 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 NDBM 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	1	package NDBM_File;
a0d0e21e	2
43c9fafc	3	BEGIN {
	4	if ($] >= 5.002) {
	5	use strict;
	6	}
	7	}
96318ac8	8
96318ac8	9	require Tie::Hash;
cb50131a	10	use XSLoader ();
a0d0e21e	11
cb50131a	12	our @ISA = qw(Tie::Hash);
cb50131a	13	our $VERSION = "1.03";
c07a80fd	14
146174a9	15	XSLoader::load 'NDBM_File', $VERSION;
a0d0e21e	16
	17	1;
	18
	19	__END__
a5f75d66	20
	21	=head1 NAME
	22
	23	NDBM_File - Tied access to ndbm files
	24
	25	=head1 SYNOPSIS
	26
22d4bb9c	27	use Fcntl; # For O_RDWR, O_CREAT, etc.
22d4bb9c	28	use NDBM_File;
a5f75d66	29
22d4bb9c	30	# Now read and change the hash
	31	$h{newkey} = newvalue;
	32	print $h{oldkey};
	33	...
	34
	35	untie %h;
	36
	37	=head1 DESCRIPTION
	38
	39	C<NDBM_File> establishes a connection between a Perl hash variable and
	40	a file in NDBM_File format;. You can manipulate the data in the file
	41	just as if it were in a Perl hash, but when your program exits, the
	42	data will remain in the file, to be used the next time your program
	43	runs.
a5f75d66	44
22d4bb9c	45	Use C<NDBM_File> with the Perl built-in C<tie> function to establish
	46	the connection between the variable and the file. The arguments to
	47	C<tie> should be:
a5f75d66	48
22d4bb9c	49	=over 4
	50
	51	=item 1.
	52
	53	The hash variable you want to tie.
	54
	55	=item 2.
	56
	57	The string C<"NDBM_File">. (Ths tells Perl to use the C<NDBM_File>
	58	package to perform the functions of the hash.)
	59
	60	=item 3.
	61
	62	The name of the file you want to tie to the hash.
	63
	64	=item 4.
	65
	66	Flags. Use one of:
	67
	68	=over 2
	69
	70	=item C<O_RDONLY>
	71
	72	Read-only access to the data in the file.
	73
	74	=item C<O_WRONLY>
	75
	76	Write-only access to the data in the file.
	77
	78	=item C<O_RDWR>
	79
	80	Both read and write access.
	81
	82	=back
	83
	84	If you want to create the file if it does not exist, add C<O_CREAT> to
	85	any of these, as in the example. If you omit C<O_CREAT> and the file
	86	does not already exist, the C<tie> call will fail.
	87
	88	=item 5.
	89
	90	The default permissions to use if a new file is created. The actual
	91	permissions will be modified by the user's umask, so you should
	92	probably use 0666 here. (See L<perlfunc/umask>.)
	93
	94	=back
	95
	96	=head1 DIAGNOSTICS
	97
	98	On failure, the C<tie> call returns an undefined value and probably
	99	sets C<$!> to contain the reason the file could not be tied.
	100
	101	=head2 C<ndbm 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 NDBM 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.
a5f75d66	113
22d4bb9c	114	See L<perlfunc/tie>, L<perldbmfilter>, L<Fcntl>
a5f75d66	115
a5f75d66	116	=cut