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| 1 # Copyright © 2010 Raphaël Hertzog <hertzog@debian.org> |
| 2 # |
| 3 # This program is free software; you can redistribute it and/or modify |
| 4 # it under the terms of the GNU General Public License as published by |
| 5 # the Free Software Foundation; either version 2 of the License, or |
| 6 # (at your option) any later version. |
| 7 # |
| 8 # This program is distributed in the hope that it will be useful, |
| 9 # but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 10 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 11 # GNU General Public License for more details. |
| 12 # |
| 13 # You should have received a copy of the GNU General Public License |
| 14 # along with this program. If not, see <https://www.gnu.org/licenses/>. |
| 15 |
| 16 package Dpkg::Interface::Storable; |
| 17 |
| 18 use strict; |
| 19 use warnings; |
| 20 |
| 21 our $VERSION = '1.00'; |
| 22 |
| 23 use Carp; |
| 24 |
| 25 use Dpkg::Gettext; |
| 26 use Dpkg::ErrorHandling; |
| 27 use Dpkg::Compression::FileHandle; |
| 28 |
| 29 use overload |
| 30 '""' => \&_stringify, |
| 31 'fallback' => 1; |
| 32 |
| 33 =encoding utf8 |
| 34 |
| 35 =head1 NAME |
| 36 |
| 37 Dpkg::Interface::Storable - common methods related to object serialization |
| 38 |
| 39 =head1 DESCRIPTION |
| 40 |
| 41 Dpkg::Interface::Storable is only meant to be used as parent |
| 42 class for other objects. It provides common methods that are |
| 43 all implemented on top of two basic methods parse() and output(). |
| 44 |
| 45 =head1 BASE METHODS |
| 46 |
| 47 Those methods must be provided by the object that wish to inherit |
| 48 from Dpkg::Interface::Storable so that the methods provided can work. |
| 49 |
| 50 =over 4 |
| 51 |
| 52 =item $obj->parse($fh, $desc) |
| 53 |
| 54 This methods initialize the object with the data stored in the |
| 55 filehandle. $desc is optional and is a textual description of |
| 56 the filehandle used in error messages. |
| 57 |
| 58 =item $string = $obj->output($fh) |
| 59 |
| 60 This method returns a string representation of the object in $string |
| 61 and it writes the same string to $fh (if it's defined). |
| 62 |
| 63 =back |
| 64 |
| 65 =head1 PROVIDED METHODS |
| 66 |
| 67 =over 4 |
| 68 |
| 69 =item $obj->load($filename) |
| 70 |
| 71 Initialize the object with the data stored in the file. The file can be |
| 72 compressed, it will be uncompressed on the fly by using a |
| 73 Dpkg::Compression::FileHandle object. If $filename is "-", then the |
| 74 standard input is read (no compression is allowed in that case). |
| 75 |
| 76 =cut |
| 77 |
| 78 sub load { |
| 79 my ($self, $file, @options) = @_; |
| 80 unless ($self->can('parse')) { |
| 81 croak ref($self) . ' cannot be loaded, it lacks the parse method'; |
| 82 } |
| 83 my ($desc, $fh) = ($file, undef); |
| 84 if ($file eq '-') { |
| 85 $fh = \*STDIN; |
| 86 $desc = _g('<standard input>'); |
| 87 } else { |
| 88 $fh = Dpkg::Compression::FileHandle->new(); |
| 89 open($fh, '<', $file) or syserr(_g('cannot read %s'), $file); |
| 90 } |
| 91 my $res = $self->parse($fh, $desc, @options); |
| 92 if ($file ne '-') { |
| 93 close($fh) or syserr(_g('cannot close %s'), $file); |
| 94 } |
| 95 return $res; |
| 96 } |
| 97 |
| 98 =item $obj->save($filename) |
| 99 |
| 100 Store the object in the file. If the filename ends with a known |
| 101 compression extension, it will be compressed on the fly by using a |
| 102 Dpkg::Compression::FileHandle object. If $filename is "-", then the |
| 103 standard output is used (data are written uncompressed in that case). |
| 104 |
| 105 =cut |
| 106 |
| 107 sub save { |
| 108 my ($self, $file, @options) = @_; |
| 109 unless ($self->can('output')) { |
| 110 croak ref($self) . ' cannot be saved, it lacks the output method'; |
| 111 } |
| 112 my $fh; |
| 113 if ($file eq '-') { |
| 114 $fh = \*STDOUT; |
| 115 } else { |
| 116 $fh = Dpkg::Compression::FileHandle->new(); |
| 117 open($fh, '>', $file) or syserr(_g('cannot write %s'), $file); |
| 118 } |
| 119 $self->output($fh, @options); |
| 120 if ($file ne '-') { |
| 121 close($fh) or syserr(_g('cannot close %s'), $file); |
| 122 } |
| 123 } |
| 124 |
| 125 =item "$obj" |
| 126 |
| 127 Return a string representation of the object. |
| 128 |
| 129 =cut |
| 130 |
| 131 sub _stringify { |
| 132 my ($self) = @_; |
| 133 unless ($self->can('output')) { |
| 134 croak ref($self) . ' cannot be stringified, it lacks the output method'; |
| 135 } |
| 136 return $self->output(); |
| 137 } |
| 138 |
| 139 =back |
| 140 |
| 141 =head1 AUTHOR |
| 142 |
| 143 Raphaël Hertzog <hertzog@debian.org>. |
| 144 |
| 145 =cut |
| 146 |
| 147 1; |
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