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# Copyright © 2010 Raphaël Hertzog <hertzog@debian.org>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
=encoding utf8
=head1 NAME
Dpkg::Interface::Storable - common methods related to object serialization
=head1 DESCRIPTION
Dpkg::Interface::Storable is only meant to be used as parent
class for other classes. It provides common methods that are
all implemented on top of two basic methods parse() and output().
=cut
package Dpkg::Interface::Storable 1.01;
use strict;
use warnings;
use Carp;
use Dpkg::Gettext;
use Dpkg::ErrorHandling;
use overload
'""' => \&_stringify,
'fallback' => 1;
=head1 BASE METHODS
Those methods must be provided by the class that wish to inherit
from Dpkg::Interface::Storable so that the methods provided can work.
=over 4
=item $obj->parse($fh[, $desc])
This methods initialize the object with the data stored in the
filehandle. $desc is optional and is a textual description of
the filehandle used in error messages.
=item $string = $obj->output([$fh])
This method returns a string representation of the object in $string
and it writes the same string to $fh (if it's defined).
=back
=head1 PROVIDED METHODS
=over 4
=item $obj->load($filename, %opts)
Initialize the object with the data stored in the file. The file can be
compressed, it will be decompressed on the fly by using a
L<Dpkg::Compression::FileHandle> object. If $opts{compression} is false the
decompression support will be disabled. If $filename is "-", then the
standard input is read (no compression is allowed in that case).
=cut
sub load {
my ($self, $file, %opts) = @_;
$opts{compression} //= 1;
unless ($self->can('parse')) {
croak ref($self) . ' cannot be loaded, it lacks the parse method';
}
my ($desc, $fh) = ($file, undef);
if ($file eq '-') {
$fh = \*STDIN;
$desc = g_('<standard input>');
} else {
if ($opts{compression}) {
require Dpkg::Compression::FileHandle;
$fh = Dpkg::Compression::FileHandle->new();
}
open($fh, '<', $file) or syserr(g_('cannot read %s'), $file);
}
my $res = $self->parse($fh, $desc, %opts);
if ($file ne '-') {
close($fh) or syserr(g_('cannot close %s'), $file);
}
return $res;
}
=item $obj->save($filename, %opts)
Store the object in the file. If the filename ends with a known
compression extension, it will be compressed on the fly by using a
L<Dpkg::Compression::FileHandle> object. If $opts{compression} is false the
compression support will be disabled. If $filename is "-", then the
standard output is used (data are written uncompressed in that case).
=cut
sub save {
my ($self, $file, %opts) = @_;
$opts{compression} //= 1;
unless ($self->can('output')) {
croak ref($self) . ' cannot be saved, it lacks the output method';
}
my $fh;
if ($file eq '-') {
$fh = \*STDOUT;
} else {
if ($opts{compression}) {
require Dpkg::Compression::FileHandle;
$fh = Dpkg::Compression::FileHandle->new();
}
open($fh, '>', $file) or syserr(g_('cannot write %s'), $file);
}
$self->output($fh, %opts);
if ($file ne '-') {
close($fh) or syserr(g_('cannot close %s'), $file);
}
}
=item "$obj"
Return a string representation of the object.
=cut
sub _stringify {
my $self = shift;
unless ($self->can('output')) {
croak ref($self) . ' cannot be stringified, it lacks the output method';
}
return $self->output();
}
=back
=head1 CHANGES
=head2 Version 1.01 (dpkg 1.19.0)
New options: The $obj->load() and $obj->save() methods support a new
compression option.
=head2 Version 1.00 (dpkg 1.15.6)
Mark the module as public.
=cut
1;
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