1Encode::Locale(3) User Contributed Perl Documentation Encode::Locale(3)
2
6 Encode::Locale - Determine the locale encoding
7
9 use Encode::Locale;
10 use Encode;
11 $string = decode(locale => $bytes);
13 $bytes = encode(locale => $string);
14 if (-t) {
16 binmode(STDIN, ":encoding(console_in)");
17 binmode(STDOUT, ":encoding(console_out)");
18 binmode(STDERR, ":encoding(console_out)");
19 }
20 # Processing file names passed in as arguments
22 my $uni_filename = decode(locale => $ARGV[0]);
23 open(my $fh, "<", encode(locale_fs => $uni_filename))
24 || die "Can't open '$uni_filename': $!";
25 binmode($fh, ":encoding(locale)");
26 ...
27
29 In many applications it's wise to let Perl use Unicode for the strings
30 it processes. Most of the interfaces Perl has to the outside world are
31 still byte based. Programs therefore need to decode byte strings that
32 enter the program from the outside and encode them again on the way
33 out.
34 The POSIX locale system is used to specify both the language
36 conventions requested by the user and the preferred character set to
37 consume and output. The "Encode::Locale" module looks up the charset
38 and encoding (called a CODESET in the locale jargon) and arranges for
39 the Encode module to know this encoding under the name "locale". It
40 means bytes obtained from the environment can be converted to Unicode
41 strings by calling "Encode::encode(locale => $bytes)" and converted
42 back again with "Encode::decode(locale => $string)".
43 Where file systems interfaces pass file names in and out of the program
45 we also need care. The trend is for operating systems to use a fixed
46 file encoding that don't actually depend on the locale; and this module
47 determines the most appropriate encoding for file names. The Encode
48 module will know this encoding under the name "locale_fs". For
49 traditional Unix systems this will be an alias to the same encoding as
50 "locale".
51 For programs running in a terminal window (called a "Console" on some
53 systems) the "locale" encoding is usually a good choice for what to
54 expect as input and output. Some systems allows us to query the
55 encoding set for the terminal and "Encode::Locale" will do that if
56 available and make these encodings known under the "Encode" aliases
57 "console_in" and "console_out". For systems where we can't determine
58 the terminal encoding these will be aliased as the same encoding as
59 "locale". The advice is to use "console_in" for input known to come
60 from the terminal and "console_out" for output to the terminal.
61 In addition to arranging for various Encode aliases the following
63 functions and variables are provided:
64 decode_argv( )
66 decode_argv( Encode::FB_CROAK )
67 This will decode the command line arguments to perl (the @ARGV
68 array) in-place.
69 The function will by default replace characters that can't be
71 decoded by "\x{FFFD}", the Unicode replacement character.
72 Any argument provided is passed as CHECK to underlying
74 Encode::decode() call. Pass the value "Encode::FB_CROAK" to have
75 the decoding croak if not all the command line arguments can be
76 decoded. See "Handling Malformed Data" in Encode for details on
77 other options for CHECK.
78 env( $uni_key )
80 env( $uni_key => $uni_value )
81 Interface to get/set environment variables. Returns the current
82 value as a Unicode string. The $uni_key and $uni_value arguments
83 are expected to be Unicode strings as well. Passing "undef" as
84 $uni_value deletes the environment variable named $uni_key.
85 The returned value will have the characters that can't be decoded
87 replaced by "\x{FFFD}", the Unicode replacement character.
88 There is no interface to request alternative CHECK behavior as for
90 decode_argv(). If you need that you need to call encode/decode
91 yourself. For example:
92 my $key = Encode::encode(locale => $uni_key, Encode::FB_CROAK);
94 my $uni_value = Encode::decode(locale => $ENV{$key}, Encode::FB_CROAK);
95 reinit( )
97 reinit( $encoding )
98 Reinitialize the encodings from the locale. You want to call this
99 function if you changed anything in the environment that might
100 influence the locale.
101 This function will croak if the determined encoding isn't
103 recognized by the Encode module.
104 With argument force $ENCODING_... variables to set to the given
106 value.
107 $ENCODING_LOCALE
109 The encoding name determined to be suitable for the current locale.
110 Encode know this encoding as "locale".
111 $ENCODING_LOCALE_FS
113 The encoding name determined to be suitable for file system
114 interfaces involving file names. Encode know this encoding as
115 "locale_fs".
116 $ENCODING_CONSOLE_IN
118 $ENCODING_CONSOLE_OUT
119 The encodings to be used for reading and writing output to the a
120 console. Encode know these encodings as "console_in" and
121 "console_out".
122
124 This table summarizes the mapping of the encodings set up by the
125 "Encode::Locale" module:
126 Encode | | |
128 Alias | Windows | Mac OS X | POSIX
129 ------------+---------+--------------+------------
130 locale | ANSI | nl_langinfo | nl_langinfo
131 locale_fs | ANSI | UTF-8 | nl_langinfo
132 console_in | OEM | nl_langinfo | nl_langinfo
133 console_out | OEM | nl_langinfo | nl_langinfo
134 Windows
136 Windows has basically 2 sets of APIs. A wide API (based on passing
137 UTF-16 strings) and a byte based API based a character set called ANSI.
138 The regular Perl interfaces to the OS currently only uses the ANSI
139 APIs. Unfortunately ANSI is not a single character set.
140 The encoding that corresponds to ANSI varies between different editions
142 of Windows. For many western editions of Windows ANSI corresponds to
143 CP-1252 which is a character set similar to ISO-8859-1. Conceptually
144 the ANSI character set is a similar concept to the POSIX locale CODESET
145 so this module figures out what the ANSI code page is and make this
146 available as $ENCODING_LOCALE and the "locale" Encoding alias.
147 Windows systems also operate with another byte based character set.
149 It's called the OEM code page. This is the encoding that the Console
150 takes as input and output. It's common for the OEM code page to differ
151 from the ANSI code page.
152 Mac OS X
154 On Mac OS X the file system encoding is always UTF-8 while the locale
155 can otherwise be set up as normal for POSIX systems.
156 File names on Mac OS X will at the OS-level be converted to NFD-form.
158 A file created by passing a NFC-filename will come in NFD-form from
159 readdir(). See Unicode::Normalize for details of NFD/NFC.
160 Actually, Apple does not follow the Unicode NFD standard since not all
162 character ranges are decomposed. The claim is that this avoids
163 problems with round trip conversions from old Mac text encodings. See
164 Encode::UTF8Mac for details.
165 POSIX (Linux and other Unixes)
167 File systems might vary in what encoding is to be used for filenames.
168 Since this module has no way to actually figure out what the is correct
169 it goes with the best guess which is to assume filenames are encoding
170 according to the current locale. Users are advised to always specify
171 UTF-8 as the locale charset.
172
174 I18N::Langinfo, Encode, Term::Encoding
175
177 Copyright 2010 Gisle Aas <gisle@aas.no>.
178 This library is free software; you can redistribute it and/or modify it
180 under the same terms as Perl itself.
181perl v5.36.0 2023-01-20 Encode::Locale(3)