oracular (3) Locale::Recode.3pm.gz
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)