Unicode

Introducción

Ejercicio 31.3.1   Antes de comenzar esta sección, lea los siguientes documentos:

• The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!)

La siguiente introducción esta tomada de la sección la sección 'Unicode' en perluniintro:

Unicode is a character set standard which plans to codify all of the writing systems of the world, plus many other symbols.

Unicode and ISO/IEC 10646 are coordinated standards that provide code points for characters in almost all modern character set standards, covering more than 30 writing systems and hundreds of languages, including all commercially-important modern languages.

All characters in the largest Chinese, Japanese, and Korean dictionaries are also encoded. The standards will eventually cover almost all characters in more than 250 writing systems and thousands of languages. Unicode 1.0 was released in October 1991, and 4.0 in April 2003.

A Unicode character is an abstract entity. It is not bound to any particular integer width, especially not to the C language char .

Unicode is language-neutral and display-neutral: it does not encode the language of the text and it does not generally define fonts or other graphical layout details. Unicode operates on characters and on text built from those characters.

Unicode defines characters like LATIN CAPITAL LETTER A or GREEK SMALL LETTER ALPHA and unique numbers for the characters, in this case 0x0041 and 0x03B1, respectively. These unique numbers are called code points.

The Unicode standard prefers using hexadecimal notation for the code points.

The Unicode standard uses the notation U+0041 LATIN CAPITAL LETTER A, to give the hexadecimal code point and the normative name of the character.

Unicode also defines various Unicode properties for the characters, like uppercase or lowercase, decimal digit, or punctuation; these properties are independent of the names of the characters.

Furthermore, various operations on the characters like uppercasing, lowercasing, and collating (sorting) are defined.

A Unicode character consists either of a single code point, or a base character (like LATIN CAPITAL LETTER A ), followed by one or more modifiers (like COMBINING ACUTE ACCENT ). This sequence of base character and modifiers is called a combining character sequence.

Whether to call these combining character sequences "characters" depends on your point of view. If you are a programmer, you probably would tend towards seeing each element in the sequences as one unit, or "character". The whole sequence could be seen as one "character", however, from the user's point of view, since that's probably what it looks like in the context of the user's language.

With this "whole sequence" view of characters, the total number of characters is open-ended. But in the programmer's "one unit is one character" point of view, the concept of "characters" is more deterministic.

In this document, we take that second point of view: one "character" is one Unicode code point, be it a base character or a combining character.

For some combinations, there are precomposed characters. LATIN CAPITAL LETTER A WITH ACUTE , for example, is defined as a single code point.

These precomposed characters are, however, only available for some combinations, and are mainly meant to support round-trip conversions between Unicode and legacy standards (like the ISO 8859).

In the general case, the composing method is more extensible. To support conversion between different compositions of the characters, various normalization forms to standardize representations are also defined.

Because of backward compatibility with legacy encodings, the "a unique number for every character" idea breaks down a bit: instead, there is "at least one number for every character".

The same character could be represented differently in several legacy encodings.

The converse is also not true: some code points do not have an assigned character.

• Firstly, there are unallocated code points within otherwise used blocks.
• Secondly, there are special Unicode control characters that do not represent true characters.

A common myth about Unicode is that it would be "16-bit", that is, Unicode is only represented as 0x10000 (or 65536) characters from 0x0000 to 0xFFFF . This is untrue. Since Unicode 2.0 (July 1996), Unicode has been defined all the way up to 21 bits (0x10FFFF ), and since Unicode 3.1 (March 2001), characters have been defined beyond 0xFFFF . The first 0x10000 characters are called the Plane 0, or the Basic Multilingual Plane (BMP). With Unicode 3.1, 17 (yes, seventeen) planes in all were defined-but they are nowhere near full of defined characters, yet.

Another myth is that the 256-character blocks have something to do with languages-that each block would define the characters used by a language or a set of languages. This is also untrue. The division into blocks exists, but it is almost completely accidental-an artifact of how the characters have been and still are allocated. Instead, there is a concept called scripts, which is more useful: there is

• Latin script,
• Greek script,

and so on. Scripts usually span varied parts of several blocks. For further information see Unicode::UCD:

pl@nereida:~/Lperltesting$ perl5.10.1 -wdE 0
main::(-e:1):   0
  DB<1> use Unicode::UCD qw{charinfo charscripts}
  DB<2> x charinfo(0x41)
0  HASH(0xc69a88)
   'bidi' => 'L'
   'block' => 'Basic Latin'
   'category' => 'Lu'
   'code' => 0041
   'combining' => 0
   'comment' => ''
   'decimal' => ''
   'decomposition' => ''
   'digit' => ''
   'lower' => 0061
   'mirrored' => 'N'
   'name' => 'LATIN CAPITAL LETTER A'
   'numeric' => ''
   'script' => 'Latin'
   'title' => ''
   'unicode10' => ''
   'upper' => ''
  DB<3> x @{charscripts()->{Greek}}[0..3]
0  ARRAY(0xd676a8)
   0  880
   1  883
   2  'Greek'
1  ARRAY(0xd86300)
   0  885
   1  885
   2  'Greek'
2  ARRAY(0xd6c718)
   0  886
   1  887
   2  'Greek'
3  ARRAY(0xd6c790)
   0  890
   1  890
   2  'Greek'

The Unicode code points are just abstract numbers. To input and output these abstract numbers, the numbers must be encoded or serialised somehow. Unicode defines several character encoding forms, of which UTF-8 is perhaps the most popular. UTF-8 is a variable length encoding that encodes Unicode characters as 1 to 6 bytes (only 4 with the currently defined characters). Other encodings include UTF-16 and UTF-32 and their big- and little-endian variants (UTF-8 is byte-order independent) The ISO/IEC 10646 defines the UCS-2 and UCS-4 encoding forms.

Operadores, STDOUT y Unicode

Considere el siguiente programa:

lhp@nereida:~/Lperl/src/testing$ cat -n useutf8_1.pl
     1  #!/usr/local/bin/perl -w
     2  use strict;
     3
     4  my $x = 'áéíóúñ€';
     5  print "$x\n";
     6  print length($x)."\n";

Cuando lo ejecutamos obtenemos la salida:

lhp@nereida:~/Lperl/src/testing$ useutf8_1.pl
áéíóúñ€
15

Perl tiene dos modos de procesamiento de datos: el modo byte y el modo carácter. El modo por defecto es el modo byte. Este modo es conveniente cuando se trabaja con ficheros binarios (p. ej. una imagen JPEG) y con texto codificado con un código que requiere un sólo byte por carácter como es el caso de Latin 1.

En efecto, la cadena 'áéíóúñ€' - que es una cadena unicode codificada en UTF-8 - tiene una longitud de 15 bytes. El asunto es que no es lo mismo la longitud en bytes que la longitud en caracteres cuando nos salimos de ASCII y Latin1. Si queremos que length devuelva la longitud en caracteres usemos utf8 :

lhp@nereida:~/Lperl/src/testing$ cat -n useutf8_2.pl
     1  #!/usr/local/bin/perl -w
     2  use strict;
     3  use utf8;
     4
     5  my $x = 'áéíóúñ€';
     6  print "$x\n";
     7  print length($x)."\n";

Al ejecutar obtenemos la longitud en caracteres:

lhp@nereida:~/Lperl/src/testing$ useutf8_2.pl
Wide character in print at ./useutf8_2.pl line 6.
áéíóúñ€
7

Ahora length retorna la longitud en caracteres.

Obsérvese el mensaje de advertencia. Si queremos asegurar el buen funcionamiento de la salida por STDOUT con caracteres codificados en UTF-8 debemos llamar a binmode sobre STDOUT con la capa ':utf8':

lhp@nereida:~/Lperl/src/testing$ cat -n useutf8_3.pl
     1  #!/usr/local/bin/perl -w
     2  use strict;
     3  use utf8;
     4  binmode(STDOUT, ':utf8');
     5
     6  my $x = 'áéíóúñ€';
     7  print "$x\n";
     8  print length($x)."\n";

El mensaje de advertencia desaparece:

lhp@nereida:~/Lperl/src/testing$ useutf8_3.pl
áéíóúñ€
7

Usando la opción -C del intérprete Perl se puede conseguir el mismo resultado:

lhp@nereida:~/Lperl/src/testing$ perl useutf8_1.pl
áéíóúñ€
15
lhp@nereida:~/Lperl/src/testing$ perl -Mutf8 -COE useutf8_1.pl
áéíóúñ€
7

Lea perldoc perlrun para mas información sobre estas opciones:

As of 5.8.1, the "-C" can be followed either by a number or a list of option
letters.  The letters, their numeric values, and effects are as follows;
listing the letters is equal to summing the numbers.

  I     1    STDIN is assumed to be in UTF-8
  O     2    STDOUT will be in UTF-8
  E     4    STDERR will be in UTF-8
  S     7    I + O + E
  i     8    UTF-8 is the default PerlIO layer for input streams
  o    16    UTF-8 is the default PerlIO layer for output streams
  D    24    i + o
  A    32    the @ARGV elements are expected to be strings encoded in UTF-8
  L    64    normally the "IOEioA" are unconditional,
             the L makes them conditional on the locale environment
             variables (the LC_ALL, LC_TYPE, and LANG, in the order
             of decreasing precedence) -- if the variables indicate
             UTF-8, then the selected "IOEioA" are in effect

En Perl las cadenas tienen un flag que indica si la representación interna de la cadena es utf-8. La función is_utf8 de utf8 permite conocer si una cadena esta almacenada internamente como utf-8:

pl@nereida:~/Lperltesting$ cat -n is_utf8.pl
     1  #!/usr/local/lib/perl/5.10.1/bin/perl5.10.1 -w -COE
     2  use strict;
     3  use utf8;
     4
     5  my $x = 'áéíóúñ€';
     6  my $y = 'abc';
     7  my $z = 'αβγδη';
     8  print "$x is utf8\n" if utf8::is_utf8($x);
     9  print "$y is utf8\n" if utf8::is_utf8($y);
    10  print "$z is utf8\n" if utf8::is_utf8($z);

Al ejecutar produce la salida:

pl@nereida:~/Lperltesting$ ./is_utf8.pl
áéíóúñ€ is utf8
αβγδη is utf8

Ficheros Unicode en vim

La documentación de vim sobre modo Multi-byte support relativa a unicode dice:

Useful commands:

• ga shows the decimal, hexadecimal and octal value of the character under the cursor. If there are composing characters these are shown too. (If the message is truncated, use ":messages").
• g8 shows the bytes used in a UTF-8 character, also the composing characters, as hex numbers.
• :set encoding=utf-8 fileencodings= forces using UTF-8 for all files. The default is to use the current locale for 'encoding' and set 'fileencodings' to automatically detect the encoding of a file.

....

If your current locale is in an utf-8 encoding, Vim will automatically start in utf-8 mode.

If you are using another locale:

        set encoding=utf-8

En nuestro caso, tenemos las locale usando utf-8:

casiano@millo:~/Lperltesting$ locale
LANG=es_ES.UTF-8
LC_CTYPE="es_ES.UTF-8"
LC_NUMERIC="es_ES.UTF-8"
LC_TIME="es_ES.UTF-8"
LC_COLLATE="es_ES.UTF-8"
LC_MONETARY="es_ES.UTF-8"
LC_MESSAGES="es_ES.UTF-8"
LC_PAPER="es_ES.UTF-8"
LC_NAME="es_ES.UTF-8"
LC_ADDRESS="es_ES.UTF-8"
LC_TELEPHONE="es_ES.UTF-8"
LC_MEASUREMENT="es_ES.UTF-8"
LC_IDENTIFICATION="es_ES.UTF-8"
LC_ALL=

Hay varias formas de crear ficheros Unicode en lenguajes fuera del rango del latin1 con vim.

Los caracteres unicode en la línea 3 del siguiente fichero han sido generados en vim insertandolos mediante su codificación usando la secuencia CTRL-V u hexcode.

lhp@nereida:~/Lperl/src/testing$ cat -n utf8file.txt
     1  áéíóúñÑ
     2  àèìòùÇç
     3  ェッニは大き

En concreto los códigos creo que fueron: 30a7, 30c3, 30cb, 306f, 5927 y 304d.

pl@nereida:~/Lperltesting$ perl5.10.1 -C7 -E 'say chr($_) for (0x30a7, 0x30c3, 0x30cb, 0x306f,  0x5927, 0x304d)'
ェ
ッ
ニ
は
大
き

Una forma mas cómoda de insertar caracteres Unicode en vim es usar keymaps :

1. Vea que keymaps están disponibles ejecutando el comando vim:

   :echo globpath(&rtp, "keymap/*.vim")
   

   Para entender el comando anterior hay que tener en cuenta que:
   • La función globpath tiene la sintáxis globpath({path}, {expr} [, {flag}]) y realiza un glob de {expr} sobre la lista de directorios en {path}.
   • La función rtp devuelve el run-time path de vim
   • El comando echo {expr1} .. muestra los valores de {expr1}, .. separados por espacios.

   Esto mostrará algo como:

   /usr/share/vim/vim70/keymap/accents.vim
   /usr/share/vim/vim70/keymap/arabic.vim
   /usr/share/vim/vim70/keymap/arabic_utf-8.vim
   /usr/share/vim/vim70/keymap/bulgarian.vim
   /usr/share/vim/vim70/keymap/canfr-win.vim
   /usr/share/vim/vim70/keymap/czech.vim
   /usr/share/vim/vim70/keymap/czech_utf-8.vim
   /usr/share/vim/vim70/keymap/esperanto.vim
   /usr/share/vim/vim70/keymap/esperanto_utf-8.vim
   /usr/share/vim/vim70/keymap/greek.vim
   /usr/share/vim/vim70/keymap/greek_cp1253.vim
   /usr/share/vim/vim70/keymap/greek_cp737.vim
   /usr/share/vim/vim70/keymap/greek_iso-8859-7.vim
   /usr/share/vim/vim70/keymap/greek_utf-8.vim
   ....
   

   Como se ve el convenio de nombres para los keymaps es:

   <language>_<encoding>.vim
   

   Sigue un ejemplo de fichero de keymap:

   $ cat -n /usr/share/vim/vim70/keymap/greek_utf-8.vim
    1 " Vim Keymap file for greek
    2 " Maintainer: Panagiotis Louridas <louridas@acm.org>
    3 " Last Updated: Thu Mar 23 23:45:02 EET 2006
    4 
    .......................................................................
   72 let b:keymap_name = "grk"
   73 loadkeymap
   74 " PUNCTUATION MARKS - SYMBOLS (GREEK SPECIFIC)
   75 "
   76 E$	<char-0x20AC>  " EURO SIGN
   ............................................................................
   115 "
   116 " GREEK LETTERS
   117 "
   118 A	<char-0x0391>   " GREEK CAPITAL LETTER ALPHA
   119 B	<char-0x0392>   " GREEK CAPITAL LETTER BETA
   120 G	<char-0x0393>   " GREEK CAPITAL LETTER GAMMA
   121 D	<char-0x0394>   " GREEK CAPITAL LETTER DELTA
   122 E	<char-0x0395>   " GREEK CAPITAL LETTER EPSILON
   123 Z	<char-0x0396>   " GREEK CAPITAL LETTER ZETA
   

2. Ahora ejecute el comando:

   :set keymap=greek
   

   Cuando estamos en modo inserción podemos conmutar entre los dos keymaps tecleando

   CTRL-^.
   

   o bien

   CTRL-6.
   

3. Compruebe con que codificación está trabajando vim:

   :set encoding
     encoding=utf-8
   

   Es posible cambiar la codificación con la que se está editando:

   :set encoding latin1
   

   Esto no modifica la codificación del fichero.
4. Para saber mas sobre como utilizar Unicode y keymaps en vim lea las ayudas sobre los tópicos:
   • :help mbyte.txt
   • :help mbyte-keymap

Apertura de ficheros UTF-8

Use la forma con tres argumentos de open y especifique la capa :utf8 para que la entrada/salida a ese fichero se procesada por dicha capa. Por ejemplo:

lhp@nereida:~/Lperl/src/testing$ cat -n abreutf8.pl
 1  #!/usr/local/bin/perl -w
 2  use strict;
 3  binmode(STDOUT, "utf8");
 4  open my $f, '<:utf8', shift();
 5  my @a = <$f>;
 6  chomp(@a);
 7  print "$_ tiene longitud ".length($_)."\n" for @a;

Al ejecutar produce una salida como esta:

lhp@nereida:~/Lperl/src/testing$ abreutf8.pl tutu
ジジェッニgfは大好あき tiene longitud 14
αβγεφγη tiene longitud 7
νμοπ;ρ^αβψδε tiene longitud 12
& ασηφδξδξδη tiene longitud 12
abc tiene longitud 3
αβγδ&αβψ tiene longitud 8

El Módulo charnames

El módulo charnames facilita la introducción de caracteres unicode:

lhp@nereida:~/Lperl/src/testing$ cat -n alfabeta.pl
 1  #!/usr/local/bin/perl -w
 2  use strict;
 3  use charnames qw{:full greek hebrew katakana};
 4  binmode(STDOUT, ':utf8');
 5
 6  print "\N{alpha}+\N{beta} = \N{pi}\n";
 7  print "\N{alef} es la primera letra del alfabeto hebreo\n";
 8  print "Un poco de Katakana: \N{sa}\N{i}\N{n}\N{mo}\n";
 9
10  # Usando el nombre completo definido en el Standard Unicode
11  print "Hello \N{WHITE SMILING FACE}\n";

Cuando se ejecuta produce una salida como:

lhp@nereida:~/Lperl/src/testing$ alfabeta.pl
α+β = ピ
א es la primera letra del alfabeto hebreo
Un poco de Katakana: サインモ
Hello ☺

Obsérvese como la salida para \N{pi} no muestra la letra griega π sino el correspondiente símbolo Katakana ピ: atención a las colisiones entre alfabetos.

Las funciones viacode y vianame son recíprocas y nos dan la relación nombre-código de un carácter:

pl@nereida:~/Lperltesting$ perl5.10.1 -COE -Mutf8 -dE 0
main::(-e:1):   0
  DB<1>   use charnames ':full'
  DB<2>  print charnames::viacode(0x2722)
FOUR TEARDROP-SPOKED ASTERISK
  DB<3> printf "%04X", charnames::vianame("FOUR TEARDROP-SPOKED ASTERISK")
2722

Expresiones Regulares y Unicode

Usando utf8 es posible usar operadores como tr y expresiones regulares sobre cadenas UTF-8:

lhp@nereida:~/Lperl/src/testing$ cat -n useutf8.pl
 1  #!/usr/local/bin/perl -w
 2  use strict;
 3  use utf8;
 4  binmode(STDOUT, ':utf8');
 5
 6  my $x = 'áéíóúñ€';
 7  print "$x\n";
 8  print length($x)."\n";
 9
10  my$y = $x;
11  $y =~ tr/áéíóúñ€/aeioun$/;
12  print "$y\n";
13
14  $y = $x;
15  $y =~ m/áéíóúñ(€)/;
16  print "$1\n";

Al ejecutar, este programa produce la salida:

lhp@nereida:~/Lperl/src/testing$ useutf8.pl
áéíóúñ€
7
aeioun$
€

Macros: Dígitos y Words

Macros como \d han sido generalizadas. Los digitos Devanagari tienen códigos del 2406 (0x966) al 2415 (0x96F):

lhp@nereida:~/Lperl/src/testing$ unicode -x 966..96f | egrep '096|\.0'
          .0 .1 .2 .3 .4 .5 .6 .7 .8 .9 .A .B .C .D .E .F
     096.  ॠ  ॡ      ।  ॥  ०  १  २  ३  ४  ५  ६  ७  ८  ९

El siguiente ejemplo muestra que expresiones regulares como \d+ reconocen los digitos Devanagari:

lhp@nereida:~/Lperl/src/testing$ cat -n regexputf8.pl
 1  #!/usr/local/bin/perl -w
 2  use strict;
 3  binmode(STDOUT, "utf8");
 4  use utf8;
 5
 6  # Digitos Devanagari del 0 al 9
 7  my @dd  = map { chr } (2406..2415);
 8  my $x = join '+', @dd;
 9  print "La interpolación ocurre: $x\n";
10  my @number = $x =~ m{(\d+)}g;
11  print "Las expresiones regulares funcionan: @number\n";
12  print "Sin embargo la conversión numérica no es automática: ".($number[0]+$number[1])."\n";

Como se indica en el programa la conversión automática de dígitos en otros juegos de caracteres no funciona. Véase la ejecución:

lhp@nereida:~/Lperl/src/testing$ regexputf8.pl
La interpolación ocurre: ०+१+२+३+४+५+६+७+८+९
Las expresiones regulares funcionan: ० १ २ ३ ४ ५ ६ ७ ८ ९
Argument "\x{967}" isn't numeric in addition (+) at ./regexputf8.pl line 12.
Argument "\x{966}" isn't numeric in addition (+) at ./regexputf8.pl line 12.
Sin embargo la conversión numérica no es automática: 0

Lo mismo ocurre con la macro\w:

lhp@nereida:~/Lperl/src/testing$ cat -n words_utf8.pl
     1  #!/usr/local/bin/perl -w
     2  use strict;
     3  use utf8;
     4  use charnames qw{greek};
     5  binmode(STDOUT, ':utf8');
     6
     7  my $x = 'áéíóúñ€αβγδη';
     8  my @w = $x =~ /(\w)/g;
     9  print "@w\n";
lhp@nereida:~/Lperl/src/testing$ words_utf8.pl
á é í ó ú ñ α β γ δ η

Semántica de Carácter versus Semántica de Byte

Cuando se procesan datos codificados en UTF-8 el punto casa con un carácter UTF-8. La macro \C puede ser utilizada para casar un byte:

pl@nereida:~/Lperltesting$ cat -n dot_utf8.pl
     1  #!/usr/local/lib/perl/5.10.1/bin/perl5.10.1 -w -COE
     2  use v5.10;
     3  use strict;
     4  use utf8;
     5
     6  my $x = 'αβγδεφ';
     7  my @w = $x =~ /(.)/g;
     8  say "@w";
     9
    10  my @v = map { ord } $x =~ /(\C)/g;
    11  say "@v";
pl@nereida:~/Lperltesting$ ./dot_utf8.pl
α β γ δ ε φ
206 177 206 178 206 179 206 180 206 181 207 134

El mismo efecto de \C puede lograrse mediante el pragma use bytes el cual cambia la semántica de caracteres a bytes:

lhp@nereida:~/Lperl/src/testing$ cat -n dot_utf8_2.pl
     1  #!/usr/local/bin/perl -w
     2  use strict;
     3  use utf8;
     4  use charnames qw{greek};
     5
     6  binmode(STDOUT, ':utf8');
     7
     8  my $x = 'αβγδεφ';
     9
    10  my @w = $x =~ /(.)/g;
    11  print "@w\n";
    12
    13  {
    14    use bytes;
    15    my @v = map { ord } $x =~ /(.)/g;
    16    print "@v\n";
    17  }

Caja e Inversión de Cadenas Unicode

El siguiente ejemplo ilustra el uso de las funciones de cambio de caja (tales como uc , lc , lcfirst y ucfirst ) asi como el uso de reverse con cadenas unicode:

lhp@nereida:~/Lperl/src/testing$ cat -n alfabeta1.pl
 1  #!/usr/local/bin/perl -w
 2  use strict;
 3  use utf8;
 4  use charnames qw{greek};
 5  binmode(STDOUT, ':utf8');
 6
 7  my $x = "\N{alpha}+\N{beta} = \N{pi}";
 8  print uc($x)."\n";
 9  print scalar(reverse($x))."\n";
10
11  my $y = "áéíóúñ";
12  print uc($y)."\n";
13  print scalar(reverse($y))."\n";

Al ejecutarse, el programa produce la salida:

lhp@nereida:~/Lperl/src/testing$ alfabeta1.pl
Α+Β = Π
π = β+α
ÁÉÍÓÚÑ
ñúóíéá

Propiedades

El estandar Unicode declara que cadenas particulares de caracteres pueden tener propiedades particulares y que una expresión regular puede casar sobre esas propiedades utilizando la notación \p{...}:

lhp@nereida:~/Lperl/src/testing$ cat -n properties.pl
 1  #!/usr/local/bin/perl -w
 2  use strict;
 3  use utf8;
 4  use charnames qw{greek};
 5  binmode(STDOUT, ':utf8');
 6
 7  my @a = ('$', 'az', '£', 'α', '€', '￥');
 8  my $x =  "@a\n";
 9
10  print /\p{CurrencySymbol}/? "$_ = Dinero!!\n" : "$_ : No hay dinero\n" for @a;
11  print /\p{Greek}/? "$_ = Griego\n" : "$_ : No es griego\n" for @a;

Al ejecutar este script obtenemos:

lhp@nereida:~/Lperl/src/testing$ properties.pl
$ = Dinero!!
az : No hay dinero
£ = Dinero!!
α : No hay dinero
€ = Dinero!!
￥ = Dinero!!
$ : No es griego
az : No es griego
£ : No es griego
α = Griego
€ : No es griego
￥ : No es griego

El módulo Unicode::Properties permite obtener las propiedades de un carácter:

casiano@millo:~$ echo $PERL5LIB
/soft/perl5lib/perl5_10_1/lib/:/soft/perl5lib/perl5_10_1/lib/perl5:/soft/perl5lib/perl5_10_1/share/perl/5.8.8/
casiano@millo:~$ perl5.10.1 -COE -Mutf8 -dE 0
main::(-e:1):   0
  DB<1> use Unicode::Properties 'uniprops'
  DB<2> x  uniprops ('☺'); # Unicode smiley face
0  'Alphabetic'
1  'Any'
2  'Assigned'
3  'IDContinue'
4  'IDStart'
5  'InLatin1Supplement'
6  'Latin'
7  'Lowercase'

Conversores

Hay un buen número de utilidades de conversión

• unicode permite hacer consultas sobre los caracteres unicode:

  lhp@nereida:~/Lbook$ unicode 'hebrew letter alef'
  U+05D0 HEBREW LETTER ALEF
  UTF-8: d7 90  UTF-16BE: 05d0  Decimal: א
  א
  Category: Lo (Letter, Other)
  Bidi: R (Right-to-Left)
  
  U+FB2E HEBREW LETTER ALEF WITH PATAH
  UTF-8: ef ac ae  UTF-16BE: fb2e  Decimal: אַ
  אַ
  Category: Lo (Letter, Other)
  Bidi: R (Right-to-Left)
  Decomposition: 05D0 05B7
  ...
  

• iconv permite la conversión entre codificaciones. El siguiente programa usa iconv para convertir ficheros latin1 a utf-8:

   1  #!/usr/local/bin/perl -w
   2  use strict;
   3  use warnings;
   4  for my $file (@ARGV) {
   5    my $ifile = "$file.ISO_8859-15";
   6
   7    system("cp $file $ifile");
   8    system("iconv -f ISO_8859-15 -t UTF-8 $ifile > $file");
   9  }
  

• piconv viene con las distribuciones de Perl superiores a la 5.8
• paps permite imprimir ficheros de texto conteniendo unicode

  casiano@nereida:~/Lwiley_book_tracer/Coordinado$ paps --help
  Usage:
    paps [OPTION...] [text file]
  
  Help Options:
    -?, --help              Show help options
  
  Application Options:
    --landscape             Landscape output. (Default: portrait)
    --columns=NUM           Number of columns output. (Default: 1)
    --font_scale=NUM        Font scaling. (Default: 12)
    --family=FAMILY         Pango FT2 font family. (Default: Monospace)
    --rtl                   Do rtl layout.
    --justify               Do justify the lines.
    --paper=PAPER           Choose paper size. Known paper sizes are legal,
                            letter, a4. (Default: a4)
    --bottom-margin=NUM     Set bottom margin. (Default: 36)
    --top-margin=NUM        Set top margin. (Default: 36)
    --right-margin=NUM      Set right margin. (Default: 36)
    --left-margin=NUM       Set left margin. (Default: 36)
    --header                Draw page header for each page.
  

Véase también

• La documentación en perluniintro (perldoc perluniintro)
• La documentación en perlunicode
• Enrique Nell: Unicode for Perl Programmers
• Unicode 5.2 Character Code Charts
• Perl Unicode Advice
• Unicode-processing issues in Perl and how to cope with it