Locale::Recode(3pm) User Contributed Perl Documentation Locale::Recode(3pm)
NAME
Locale::Recode - Object-Oriented Portable Charset Conversion
SYNOPSIS
use Locale::Recode;
$cd = Locale::Recode->new (from => 'UTF-8',
to => 'ISO-8859-1');
die $cd->getError if $cd->getError;
$cd->recode ($text) or die $cd->getError;
$mime_name = Locale::Recode->resolveAlias ('latin-1');
$supported = Locale::Recode->getSupported;
$complete = Locale::Recode->getCharsets;
DESCRIPTION
This module provides routines that convert textual data from one
codeset to another in a portable way. The module has been started
before Encode(3) was written. It's main purpose today is to provide
charset conversion even when Encode(3) is not available on the system.
It should also work for older Perl versions without Unicode support.
Internally Locale::Recode(3) will use Encode(3) whenever possible, to
allow for a faster conversion and for a wider range of supported
charsets, and will only fall back to the Perl implementation when
Encode(3) is not available or does not support a particular charset
that Locale::Recode(3) does.
Locale::Recode(3) is part of libintl-perl, and it's main purpose is
actually to implement a portable charset conversion framework for the
message translation facilities described in Locale::TextDomain(3).
CONSTRUCTOR
The constructor "new()" requires two named arguments:
from
The encoding of the original data. Case doesn't matter, aliases
are resolved.
to The target encoding. Again, case doesn't matter, and aliases are
resolved.
The constructor will never fail. In case of an error, the object's
internal state is set to bad and it will refuse to do any conversions.
You can inquire the reason for the failure with the method getError().
OBJECT METHODS
The following object methods are available.
recode (STRING)
Converts STRING from the source encoding into the destination
encoding. In case of success, a truth value is returned, false
otherwise. You can inquire the reason for the failure with the
method getError().
getError
Returns either false if the object is not in an error state or an
error message.
CLASS METHODS
The object provides some additional class methods:
getSupported
Returns a reference to a list of all supported charsets. This may
implicitly load additional Encode(3) conversions like
Encode::HanExtra(3) which may produce considerable load on your
system.
The method is therefore not intended for regular use but rather for
getting resp. displaying once a list of available encodings.
The members of the list are all converted to uppercase!
getCharsets
Like getSupported() but also returns all available aliases.
SUPPORTED CHARSETS
The range of supported charsets is system-dependent. The following
somewhat special charsets are always available:
UTF-8
UTF-8 is available independently of your Perl version. For Perl
5.6 or better or in the presence of Encode(3), conversions are not
done in Perl but with the interfaces provided by these facilities
which are written in C, hence much faster.
Encoding data into UTF-8 is fast, even if it is done in Perl.
Decoding it in Perl may become quite slow. If you frequently have
to decode UTF-8 with Locale::Recode you will probably want to make
sure that you do that with Perl 5.6 or beter, or install Encode(3)
to speed up things.
INTERNAL
UTF-8 is fast to write but hard to read for applications. It is
therefore not the worst for internal string representation but not
far from that. Locale::Recode(3) stores strings internally as a
reference to an array of integer values like most programming
languages (Perl is an exception) do, trading memory for
performance.
The integer values are the UCS-4 codes of the characters in host
byte order.
The encoding INTERNAL is directly available via Locale::Recode(3)
but of course you should not really use it for data exchange,
unless you know what you are doing.
Locale::Recode(3) has native support for a plethora of other encodings,
most of them 8 bit encodings that are fast to decode, including most
encodings used on popular micros like the ISO-8859-* series of
encodings, most Windows-* encodings (also known as CP*), Macintosh,
Atari, etc.
NAMES AND ALIASES
Each charset resp. encoding is available internally under a unique
name. Whenever the information was available, the preferred MIME name
(see <http://www.iana.org/assignments/character-sets/>) was chosen as
the internal name.
Alias handling is quite strict. The module does not make wild guesses
at what you mean ("What's the meaning of the acronym JIS" is a valid
alias for "7bit-jis" in Encode(3) ....) but aims at providing common
aliases only. The same applies to so-called aliases that are really
mistakes, like "utf8" for UTF-8.
The module knows all aliases that are listed with the IANA character
set registry (<http://www.iana.org/assignments/character-sets/>), plus
those known to libiconv version 1.8, and a bunch of additional ones.
CONVERSION TABLES
The conversion tables have either been taken from official sources like
the IANA or the Unicode Consortium, from Bruno Haible's libiconv, or
from the sources of the GNU libc and the regression tests for libintl-
perl will check for conformance here. For some encodings this data
differs from Encode(3)'s data which would cause these tests to fail.
In these cases, the module will not invoke the Encode(3) methods, but
will fall back to the internal implementation for the sake of
consistency.
The few encodings that are affected are so simple that you will not
experience any real performance penalty unless you convert large chunks
of data. But the package is not really intended for such use anyway,
and since Encode(3) is relatively new, I rather think that the
differences are bugs in Encode which will be fixed soon.
BUGS
The module should provide fall back conversions for other Unicode
encoding schemes like UCS-2, UCS-4 (big- and little-endian).
The pure Perl UTF-8 decoder will not always handle corrupt UTF-8
correctly, especially at the end and at the beginning of the string.
This is not likely to be fixed, since the module's intention is not to
be a consistency checker for UTF-8 data.
AUTHOR
Copyright (C) 2002-2017 Guido Flohr <http://www.guido-flohr.net/>
(<mailto:guido.flohr@cantanea.com>), all rights reserved. See the
source code for details!code for details!
SEE ALSO
Encode(3), iconv(3), iconv(1), recode(1), perl(1)
perl v5.36.0 2022-12-22 Locale::Recode(3pm)
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