Encode::Locale(3) User Contributed Perl Documentation Encode::Locale(3)
NAME
Encode::Locale - Determine the locale encoding
SYNOPSIS
use Encode::Locale;
use Encode;
$string = decode(locale => $bytes);
$bytes = encode(locale => $string);
if (-t) {
binmode(STDIN, ":encoding(console_in)");
binmode(STDOUT, ":encoding(console_out)");
binmode(STDERR, ":encoding(console_out)");
}
# Processing file names passed in as arguments
my $uni_filename = decode(locale => $ARGV[0]);
open(my $fh, "<", encode(locale_fs => $uni_filename))
|| die "Can't open '$uni_filename': $!";
binmode($fh, ":encoding(locale)");
...
DESCRIPTION
In many applications it's wise to let Perl use Unicode for the strings
it processes. Most of the interfaces Perl has to the outside world are
still byte based. Programs therefore need to decode byte strings that
enter the program from the outside and encode them again on the way
out.
The POSIX locale system is used to specify both the language
conventions requested by the user and the preferred character set to
consume and output. The "Encode::Locale" module looks up the charset
and encoding (called a CODESET in the locale jargon) and arranges for
the Encode module to know this encoding under the name "locale". It
means bytes obtained from the environment can be converted to Unicode
strings by calling "Encode::encode(locale => $bytes)" and converted
back again with "Encode::decode(locale => $string)".
Where file systems interfaces pass file names in and out of the program
we also need care. The trend is for operating systems to use a fixed
file encoding that don't actually depend on the locale; and this module
determines the most appropriate encoding for file names. The Encode
module will know this encoding under the name "locale_fs". For
traditional Unix systems this will be an alias to the same encoding as
"locale".
For programs running in a terminal window (called a "Console" on some
systems) the "locale" encoding is usually a good choice for what to
expect as input and output. Some systems allows us to query the
encoding set for the terminal and "Encode::Locale" will do that if
available and make these encodings known under the "Encode" aliases
"console_in" and "console_out". For systems where we can't determine
the terminal encoding these will be aliased as the same encoding as
"locale". The advice is to use "console_in" for input known to come
from the terminal and "console_out" for output known to go from the
terminal.
In addition to arranging for various Encode aliases the following
functions and variables are provided:
decode_argv( )
decode_argv( Encode::FB_CROAK )
This will decode the command line arguments to perl (the @ARGV
array) in-place.
The function will by default replace characters that can't be
decoded by "\x{FFFD}", the Unicode replacement character.
Any argument provided is passed as CHECK to underlying
Encode::decode() call. Pass the value "Encode::FB_CROAK" to have
the decoding croak if not all the command line arguments can be
decoded. See "Handling Malformed Data" in Encode for details on
other options for CHECK.
env( $uni_key )
env( $uni_key => $uni_value )
Interface to get/set environment variables. Returns the current
value as a Unicode string. The $uni_key and $uni_value arguments
are expected to be Unicode strings as well. Passing "undef" as
$uni_value deletes the environment variable named $uni_key.
The returned value will have the characters that can't be decoded
replaced by "\x{FFFD}", the Unicode replacement character.
There is no interface to request alternative CHECK behavior as for
decode_argv(). If you need that you need to call encode/decode
yourself. For example:
my $key = Encode::encode(locale => $uni_key, Encode::FB_CROAK);
my $uni_value = Encode::decode(locale => $ENV{$key}, Encode::FB_CROAK);
reinit( )
reinit( $encoding )
Reinitialize the encodings from the locale. You want to call this
function if you changed anything in the environment that might
influence the locale.
This function will croak if the determined encoding isn't
recognized by the Encode module.
With argument force $ENCODING_... variables to set to the given
value.
$ENCODING_LOCALE
The encoding name determined to be suitable for the current locale.
Encode know this encoding as "locale".
$ENCODING_LOCALE_FS
The encoding name determined to be suiteable for file system
interfaces involving file names. Encode know this encoding as
"locale_fs".
$ENCODING_CONSOLE_IN
$ENCODING_CONSOLE_OUT
The encodings to be used for reading and writing output to the a
console. Encode know these encodings as "console_in" and
"console_out".
NOTES
This table summarizes the mapping of the encodings set up by the
"Encode::Locale" module:
Encode | | |
Alias | Windows | Mac OS X | POSIX
------------+---------+--------------+------------
locale | ANSI | nl_langinfo | nl_langinfo
locale_fs | ANSI | UTF-8 | nl_langinfo
console_in | OEM | nl_langinfo | nl_langinfo
console_out | OEM | nl_langinfo | nl_langinfo
Windows
Windows has basically 2 sets of APIs. A wide API (based on passing
UTF-16 strings) and a byte based API based a character set called ANSI.
The regular Perl interfaces to the OS currently only uses the ANSI
APIs. Unfortunately ANSI is not a single character set.
The encoding that corresponds to ANSI varies between different editions
of Windows. For many western editions of Windows ANSI corresponds to
CP-1252 which is a character set similar to ISO-8859-1. Conceptually
the ANSI character set is a similar concept to the POSIX locale CODESET
so this module figures out what the ANSI code page is and make this
available as $ENCODING_LOCALE and the "locale" Encoding alias.
Windows systems also operate with another byte based character set.
It's called the OEM code page. This is the encoding that the Console
takes as input and output. It's common for the OEM code page to differ
from the ANSI code page.
Mac OS X
On Mac OS X the file system encoding is always UTF-8 while the locale
can otherwise be set up as normal for POSIX systems.
File names on Mac OS X will at the OS-level be converted to NFD-form.
A file created by passing a NFC-filename will come in NFD-form from
readdir(). See Unicode::Normalize for details of NFD/NFC.
Actually, Apple does not follow the Unicode NFD standard since not all
character ranges are decomposed. The claim is that this avoids
problems with round trip conversions from old Mac text encodings. See
Encode::UTF8Mac for details.
POSIX (Linux and other Unixes)
File systems might vary in what encoding is to be used for filenames.
Since this module has no way to actually figure out what the is correct
it goes with the best guess which is to assume filenames are encoding
according to the current locale. Users are advised to always specify
UTF-8 as the locale charset.
SEE ALSO
I18N::Langinfo, Encode
AUTHOR
Copyright 2010 Gisle Aas <gisle AT aas.no>.
This library is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
perl v5.16.3 2012-02-11 Encode::Locale(3)
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