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 implicitely 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 availabe 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) 2002-2009, Guido Flohr <guido@imperia.net>, all rights
reserved. See the source code for details.
This software is contributed to the Perl community by Imperia
(<
http://www.imperia.net/>).
SEE ALSO¶
Encode(3),
iconv(3),
iconv(1),
recode(1),
perl(1)
POD ERRORS¶
Hey!
The above document had some coding errors, which are explained
below:
- Around line 370:
- =cut found outside a pod block. Skipping to next
block.
