NAME¶
perlunicook - cookbookish examples of handling Unicode in Perl
DESCRIPTION¶
This manpage contains short recipes demonstrating how to handle common Unicode
operations in Perl, plus one complete program at the end. Any undeclared
variables in individual recipes are assumed to have a previous appropriate
value in them.
EXAMPLES¶
X 0: Standard preamble¶
Unless otherwise notes, all examples below require this standard preamble to
work correctly, with the "#!" adjusted to work on your system:
#!/usr/bin/env perl
use utf8; # so literals and identifiers can be in UTF-8
use v5.12; # or later to get "unicode_strings" feature
use strict; # quote strings, declare variables
use warnings; # on by default
use warnings qw(FATAL utf8); # fatalize encoding glitches
use open qw(:std :utf8); # undeclared streams in UTF-8
use charnames qw(:full :short); # unneeded in v5.16
This
does make even Unix programmers "binmode" your binary
streams, or open them with ":raw", but that's the only way to get at
them portably anyway.
WARNING: "use autodie" (pre 2.26) and "use open" do
not get along with each other.
X 1: Generic Unicode-savvy filter¶
Always decompose on the way in, then recompose on the way out.
use Unicode::Normalize;
while (<>) {
$_ = NFD($_); # decompose + reorder canonically
...
} continue {
print NFC($_); # recompose (where possible) + reorder canonically
}
X 2: Fine-tuning Unicode warnings¶
As of v5.14, Perl distinguishes three subclasses of UTFX8 warnings.
use v5.14; # subwarnings unavailable any earlier
no warnings "nonchar"; # the 66 forbidden non-characters
no warnings "surrogate"; # UTF-16/CESU-8 nonsense
no warnings "non_unicode"; # for codepoints over 0x10_FFFF
X 3: Declare source in utf8 for identifiers and literals¶
Without the all-critical "use utf8" declaration, putting UTFX8 in your
literals and identifiers wonXt work right. If you used the standard preamble
just given above, this already happened. If you did, you can do things like
this:
use utf8;
my $measure = "Aangstroem";
my @Xsoft = qw( cp852 cp1251 cp1252 );
my @XXXXXXXXX = qw( XXXX XXXXX );
my @X = qw( koi8-f koi8-u koi8-r );
my $motto = "X X X"; # FAMILY, GROWING HEART, DROMEDARY CAMEL
If you forget "use utf8", high bytes will be misunderstood as separate
characters, and nothing will work right.
X 4: Characters and their numbers¶
The "ord" and "chr" functions work transparently on all
codepoints, not just on ASCII alone X nor in fact, not even just on Unicode
alone.
# ASCII characters
ord("A")
chr(65)
# characters from the Basic Multilingual Plane
ord("X")
chr(0x3A3)
# beyond the BMP
ord("X") # MATHEMATICAL ITALIC SMALL N
chr(0x1D45B)
# beyond Unicode! (up to MAXINT)
ord("\x{20_0000}")
chr(0x20_0000)
X 5: Unicode literals by character number¶
In an interpolated literal, whether a double-quoted string or a regex, you may
specify a character by its number using the "\x{
HHHHHH}"
escape.
String: "\x{3a3}"
Regex: /\x{3a3}/
String: "\x{1d45b}"
Regex: /\x{1d45b}/
# even non-BMP ranges in regex work fine
/[\x{1D434}-\x{1D467}]/
X 6: Get character name by number¶
use charnames ();
my $name = charnames::viacode(0x03A3);
X 7: Get character number by name¶
use charnames ();
my $number = charnames::vianame("GREEK CAPITAL LETTER SIGMA");
X 8: Unicode named characters¶
Use the "\N{
charname}" notation to get the character by that
name for use in interpolated literals (double-quoted strings and regexes). In
v5.16, there is an implicit
use charnames qw(:full :short);
But prior to v5.16, you must be explicit about which set of charnames you want.
The ":full" names are the official Unicode character name, alias, or
sequence, which all share a namespace.
use charnames qw(:full :short latin greek);
"\N{MATHEMATICAL ITALIC SMALL N}" # :full
"\N{GREEK CAPITAL LETTER SIGMA}" # :full
Anything else is a Perl-specific convenience abbreviation. Specify one or more
scripts by names if you want short names that are script-specific.
"\N{Greek:Sigma}" # :short
"\N{ae}" # latin
"\N{epsilon}" # greek
The v5.16 release also supports a ":loose" import for loose matching
of character names, which works just like loose matching of property names:
that is, it disregards case, whitespace, and underscores:
"\N{euro sign}" # :loose (from v5.16)
X 9: Unicode named sequences¶
These look just like character names but return multiple codepoints. Notice the
%vx vector-print functionality in "printf".
use charnames qw(:full);
my $seq = "\N{LATIN CAPITAL LETTER A WITH MACRON AND GRAVE}";
printf "U+%v04X\n", $seq;
U+0100.0300
X 10: Custom named characters¶
Use ":alias" to give your own lexically scoped nicknames to existing
characters, or even to give unnamed private-use characters useful names.
use charnames ":full", ":alias" => {
ecute => "LATIN SMALL LETTER E WITH ACUTE",
"APPLE LOGO" => 0xF8FF, # private use character
};
"\N{ecute}"
"\N{APPLE LOGO}"
X 11: Names of CJK codepoints¶
Sinograms like XXXX come back with character names of "CJK UNIFIED
IDEOGRAPH-6771" and "CJK UNIFIED IDEOGRAPH-4EAC", because their
XnamesX vary. The CPAN "Unicode::Unihan" module has a large database
for decoding these (and a whole lot more), provided you know how to understand
its output.
# cpan -i Unicode::Unihan
use Unicode::Unihan;
my $str = "XX";
my $unhan = new Unicode::Unihan;
for my $lang (qw(Mandarin Cantonese Korean JapaneseOn JapaneseKun)) {
printf "CJK $str in %-12s is ", $lang;
say $unhan->$lang($str);
}
prints:
CJK XX in Mandarin is DONG1JING1
CJK XX in Cantonese is dung1ging1
CJK XX in Korean is TONGKYENG
CJK XX in JapaneseOn is TOUKYOU KEI KIN
CJK XX in JapaneseKun is HIGASHI AZUMAMIYAKO
If you have a specific romanization scheme in mind, use the specific module:
# cpan -i Lingua::JA::Romanize::Japanese
use Lingua::JA::Romanize::Japanese;
my $k2r = new Lingua::JA::Romanize::Japanese;
my $str = "XX";
say "Japanese for $str is ", $k2r->chars($str);
prints
Japanese for XX is toukyou
X 12: Explicit encode/decode¶
On rare occasion, such as a database read, you may be given encoded text you
need to decode.
use Encode qw(encode decode);
my $chars = decode("shiftjis", $bytes, 1);
# OR
my $bytes = encode("MIME-Header-ISO_2022_JP", $chars, 1);
For streams all in the same encoding, don't use encode/decode; instead set the
file encoding when you open the file or immediately after with
"binmode" as described later below.
X 13: Decode program arguments as utf8¶
$ perl -CA ...
or
$ export PERL_UNICODE=A
or
use Encode qw(decode_utf8);
@ARGV = map { decode_utf8($_, 1) } @ARGV;
X 14: Decode program arguments as locale encoding¶
# cpan -i Encode::Locale
use Encode qw(locale);
use Encode::Locale;
# use "locale" as an arg to encode/decode
@ARGV = map { decode(locale => $_, 1) } @ARGV;
X 15: Declare STD{IN,OUT,ERR} to be utf8¶
Use a command-line option, an environment variable, or else call
"binmode" explicitly:
$ perl -CS ...
or
$ export PERL_UNICODE=S
or
use open qw(:std :utf8);
or
binmode(STDIN, ":utf8");
binmode(STDOUT, ":utf8");
binmode(STDERR, ":utf8");
X 16: Declare STD{IN,OUT,ERR} to be in locale encoding¶
# cpan -i Encode::Locale
use Encode;
use Encode::Locale;
# or as a stream for binmode or open
binmode STDIN, ":encoding(console_in)" if -t STDIN;
binmode STDOUT, ":encoding(console_out)" if -t STDOUT;
binmode STDERR, ":encoding(console_out)" if -t STDERR;
X 17: Make file I/O default to utf8¶
Files opened without an encoding argument will be in UTF-8:
$ perl -CD ...
or
$ export PERL_UNICODE=D
or
use open qw(:utf8);
X 18: Make all I/O and args default to utf8¶
$ perl -CSDA ...
or
$ export PERL_UNICODE=SDA
or
use open qw(:std :utf8);
use Encode qw(decode_utf8);
@ARGV = map { decode_utf8($_, 1) } @ARGV;
X 19: Open file with specific encoding¶
Specify stream encoding. This is the normal way to deal with encoded text, not
by calling low-level functions.
# input file
open(my $in_file, "< :encoding(UTF-16)", "wintext");
OR
open(my $in_file, "<", "wintext");
binmode($in_file, ":encoding(UTF-16)");
THEN
my $line = <$in_file>;
# output file
open($out_file, "> :encoding(cp1252)", "wintext");
OR
open(my $out_file, ">", "wintext");
binmode($out_file, ":encoding(cp1252)");
THEN
print $out_file "some text\n";
More layers than just the encoding can be specified here. For example, the
incantation ":raw :encoding(UTF-16LE) :crlf" includes implicit CRLF
handling.
X 20: Unicode casing¶
Unicode casing is very different from ASCII casing.
uc("henry X") # "HENRY X"
uc("tschuess") # "TSCHUeSS" notice ss => SS
# both are true:
"tschuess" =~ /TSCHUeSS/i # notice ss => SS
"XXXXXXX" =~ /XXXXXXX/i # notice X,X,X sameness
X 21: Unicode case-insensitive comparisons¶
Also available in the CPAN Unicode::CaseFold module, the new "fc"
XfoldcaseX function from v5.16 grants access to the same Unicode casefolding
as the "/i" pattern modifier has always used:
use feature "fc"; # fc() function is from v5.16
# sort case-insensitively
my @sorted = sort { fc($a) cmp fc($b) } @list;
# both are true:
fc("tschuess") eq fc("TSCHUeSS")
fc("XXXXXXX") eq fc("XXXXXXX")
X 22: Match Unicode linebreak sequence in regex¶
A Unicode linebreak matches the two-character CRLF grapheme or any of seven
vertical whitespace characters. Good for dealing with textfiles coming from
different operating systems.
\R
s/\R/\n/g; # normalize all linebreaks to \n
X 23: Get character category¶
Find the general category of a numeric codepoint.
use Unicode::UCD qw(charinfo);
my $cat = charinfo(0x3A3)->{category}; # "Lu"
X 24: Disabling Unicode-awareness in builtin charclasses¶
Disable "\w", "\b", "\s", "\d", and the
POSIX classes from working correctly on Unicode either in this scope, or in
just one regex.
use v5.14;
use re "/a";
# OR
my($num) = $str =~ /(\d+)/a;
Or use specific un-Unicode properties, like "\p{ahex}" and
"\p{POSIX_Digit"}. Properties still work normally no matter what
charset modifiers ("/d /u /l /a /aa") should be effect.
X 25: Match Unicode properties in regex with \p, \P¶
These all match a single codepoint with the given property. Use "\P"
in place of "\p" to match one codepoint lacking that property.
\pL, \pN, \pS, \pP, \pM, \pZ, \pC
\p{Sk}, \p{Ps}, \p{Lt}
\p{alpha}, \p{upper}, \p{lower}
\p{Latin}, \p{Greek}
\p{script=Latin}, \p{script=Greek}
\p{East_Asian_Width=Wide}, \p{EA=W}
\p{Line_Break=Hyphen}, \p{LB=HY}
\p{Numeric_Value=4}, \p{NV=4}
X 26: Custom character properties¶
Define at compile-time your own custom character properties for use in regexes.
# using private-use characters
sub In_Tengwar { "E000\tE07F\n" }
if (/\p{In_Tengwar}/) { ... }
# blending existing properties
sub Is_GraecoRoman_Title {<<'END_OF_SET'}
+utf8::IsLatin
+utf8::IsGreek
&utf8::IsTitle
END_OF_SET
if (/\p{Is_GraecoRoman_Title}/ { ... }
X 27: Unicode normalization¶
Typically render into NFD on input and NFC on output. Using NFKC or NFKD
functions improves recall on searches, assuming you've already done to the
same text to be searched. Note that this is about much more than just pre-
combined compatibility glyphs; it also reorders marks according to their
canonical combining classes and weeds out singletons.
use Unicode::Normalize;
my $nfd = NFD($orig);
my $nfc = NFC($orig);
my $nfkd = NFKD($orig);
my $nfkc = NFKC($orig);
X 28: Convert non-ASCII Unicode numerics¶
Unless youXve used "/a" or "/aa", "\d" matches
more than ASCII digits only, but PerlXs implicit string-to-number conversion
does not current recognize these. HereXs how to convert such strings manually.
use v5.14; # needed for num() function
use Unicode::UCD qw(num);
my $str = "got X and XXXX and X and here";
my @nums = ();
while ($str =~ /(\d+|\N)/g) { # not just ASCII!
push @nums, num($1);
}
say "@nums"; # 12 4567 0.875
use charnames qw(:full);
my $nv = num("\N{RUMI DIGIT ONE}\N{RUMI DIGIT TWO}");
X 29: Match Unicode grapheme cluster in regex¶
Programmer-visible XcharactersX are codepoints matched by "/./s", but
user-visible XcharactersX are graphemes matched by "/\X/".
# Find vowel *plus* any combining diacritics,underlining,etc.
my $nfd = NFD($orig);
$nfd =~ / (?=[aeiou]) \X /xi
# match and grab five first graphemes
my($first_five) = $str =~ /^ ( \X{5} ) /x;
# cpan -i Unicode::GCString
use Unicode::GCString;
my $gcs = Unicode::GCString->new($str);
my $first_five = $gcs->substr(0, 5);
X 32: Reverse string by grapheme¶
Reversing by codepoint messes up diacritics, mistakenly converting "creme
brulee" into "eelXurb emXerc" instead of into "eelurb
emerc"; so reverse by grapheme instead. Both these approaches work right
no matter what normalization the string is in:
$str = join("", reverse $str =~ /\X/g);
# OR: cpan -i Unicode::GCString
use Unicode::GCString;
$str = reverse Unicode::GCString->new($str);
X 33: String length in graphemes¶
The string "brulee" has six graphemes but up to eight codepoints. This
counts by grapheme, not by codepoint:
my $str = "brulee";
my $count = 0;
while ($str =~ /\X/g) { $count++ }
# OR: cpan -i Unicode::GCString
use Unicode::GCString;
my $gcs = Unicode::GCString->new($str);
my $count = $gcs->length;
X 34: Unicode column-width for printing¶
PerlXs "printf", "sprintf", and "format" think all
codepoints take up 1 print column, but many take 0 or 2. Here to show that
normalization makes no difference, we print out both forms:
use Unicode::GCString;
use Unicode::Normalize;
my @words = qw/creme brulee/;
@words = map { NFC($_), NFD($_) } @words;
for my $str (@words) {
my $gcs = Unicode::GCString->new($str);
my $cols = $gcs->columns;
my $pad = " " x (10 - $cols);
say str, $pad, " |";
}
generates this to show that it pads correctly no matter the normalization:
creme |
creXme |
brulee |
bruXleXe |
X 35: Unicode collation¶
Text sorted by numeric codepoint follows no reasonable alphabetic order; use the
UCA for sorting text.
use Unicode::Collate;
my $col = Unicode::Collate->new();
my @list = $col->sort(@old_list);
See the
ucsort program from the Unicode::Tussle CPAN module for a
convenient command-line interface to this module.
X 36: Case- and accent-insensitive Unicode sort¶
Specify a collation strength of level 1 to ignore case and diacritics, only
looking at the basic character.
use Unicode::Collate;
my $col = Unicode::Collate->new(level => 1);
my @list = $col->sort(@old_list);
X 37: Unicode locale collation¶
Some locales have special sorting rules.
# either use v5.12, OR: cpan -i Unicode::Collate::Locale
use Unicode::Collate::Locale;
my $col = Unicode::Collate::Locale->new(locale => "de__phonebook");
my @list = $col->sort(@old_list);
The
ucsort program mentioned above accepts a "--locale"
parameter.
X 38: Making "cmp" work on text instead of codepoints¶
Instead of this:
@srecs = sort {
$b->{AGE} <=> $a->{AGE}
||
$a->{NAME} cmp $b->{NAME}
} @recs;
Use this:
my $coll = Unicode::Collate->new();
for my $rec (@recs) {
$rec->{NAME_key} = $coll->getSortKey( $rec->{NAME} );
}
@srecs = sort {
$b->{AGE} <=> $a->{AGE}
||
$a->{NAME_key} cmp $b->{NAME_key}
} @recs;
X 39: Case- and accent-insensitive comparisons¶
Use a collator object to compare Unicode text by character instead of by
codepoint.
use Unicode::Collate;
my $es = Unicode::Collate->new(
level => 1,
normalization => undef
);
# now both are true:
$es->eq("Garcia", "GARCIA" );
$es->eq("Marquez", "MARQUEZ");
X 40: Case- and accent-insensitive locale comparisons¶
Same, but in a specific locale.
my $de = Unicode::Collate::Locale->new(
locale => "de__phonebook",
);
# now this is true:
$de->eq("tschuess", "TSCHUESS"); # notice ue => UE, ss => SS
X 41: Unicode linebreaking¶
Break up text into lines according to Unicode rules.
# cpan -i Unicode::LineBreak
use Unicode::LineBreak;
use charnames qw(:full);
my $para = "This is a super\N{HYPHEN}long string. " x 20;
my $fmt = new Unicode::LineBreak;
print $fmt->break($para), "\n";
X 42: Unicode text in DBM hashes, the tedious way¶
Using a regular Perl string as a key or value for a DBM hash will trigger a wide
character exception if any codepoints wonXt fit into a byte. HereXs how to
manually manage the translation:
use DB_File;
use Encode qw(encode decode);
tie %dbhash, "DB_File", "pathname";
# STORE
# assume $uni_key and $uni_value are abstract Unicode strings
my $enc_key = encode("UTF-8", $uni_key, 1);
my $enc_value = encode("UTF-8", $uni_value, 1);
$dbhash{$enc_key} = $enc_value;
# FETCH
# assume $uni_key holds a normal Perl string (abstract Unicode)
my $enc_key = encode("UTF-8", $uni_key, 1);
my $enc_value = $dbhash{$enc_key};
my $uni_value = decode("UTF-8", $enc_value, 1);
X 43: Unicode text in DBM hashes, the easy way¶
HereXs how to implicitly manage the translation; all encoding and decoding is
done automatically, just as with streams that have a particular encoding
attached to them:
use DB_File;
use DBM_Filter;
my $dbobj = tie %dbhash, "DB_File", "pathname";
$dbobj->Filter_Value("utf8"); # this is the magic bit
# STORE
# assume $uni_key and $uni_value are abstract Unicode strings
$dbhash{$uni_key} = $uni_value;
# FETCH
# $uni_key holds a normal Perl string (abstract Unicode)
my $uni_value = $dbhash{$uni_key};
X 44: PROGRAM: Demo of Unicode collation and printing¶
HereXs a full program showing how to make use of locale-sensitive sorting,
Unicode casing, and managing print widths when some of the characters take up
zero or two columns, not just one column each time. When run, the following
program produces this nicely aligned output:
Creme Brulee....... X2.00
Eclair............. X1.60
Fideua............. X4.20
Hamburger.......... X6.00
Jamon Serrano...... X4.45
Linguica........... X7.00
Pate............... X4.15
Pears.............. X2.00
Peches............. X2.25
Smorbrod........... X5.75
Spaetzle............ X5.50
Xorico............. X3.00
XXXXX.............. X6.50
XXX............. X4.00
XXX............. X2.65
XXXXX......... X8.00
XXXXXXX..... X1.85
XX............... X9.99
XX............... X7.50
Here's that program; tested on v5.14.
#!/usr/bin/env perl
# umenu - demo sorting and printing of Unicode food
#
# (obligatory and increasingly long preamble)
#
use utf8;
use v5.14; # for locale sorting
use strict;
use warnings;
use warnings qw(FATAL utf8); # fatalize encoding faults
use open qw(:std :utf8); # undeclared streams in UTF-8
use charnames qw(:full :short); # unneeded in v5.16
# std modules
use Unicode::Normalize; # std perl distro as of v5.8
use List::Util qw(max); # std perl distro as of v5.10
use Unicode::Collate::Locale; # std perl distro as of v5.14
# cpan modules
use Unicode::GCString; # from CPAN
# forward defs
sub pad($$$);
sub colwidth(_);
sub entitle(_);
my %price = (
"XXXXX" => 6.50, # gyros
"pears" => 2.00, # like um, pears
"linguica" => 7.00, # spicy sausage, Portuguese
"xorico" => 3.00, # chorizo sausage, Catalan
"hamburger" => 6.00, # burgermeister meisterburger
"eclair" => 1.60, # dessert, French
"smorbrod" => 5.75, # sandwiches, Norwegian
"spaetzle" => 5.50, # Bayerisch noodles, little sparrows
"XX" => 7.50, # bao1 zi5, steamed pork buns, Mandarin
"jamon serrano" => 4.45, # country ham, Spanish
"peches" => 2.25, # peaches, French
"XXXXXXX" => 1.85, # cream-filled pastry like eclair
"XXX" => 4.00, # makgeolli, Korean rice wine
"XX" => 9.99, # sushi, Japanese
"XXX" => 2.65, # omochi, rice cakes, Japanese
"creme brulee" => 2.00, # crema catalana
"fideua" => 4.20, # more noodles, Valencian
# (Catalan=fideuada)
"pate" => 4.15, # gooseliver paste, French
"XXXXX" => 8.00, # okonomiyaki, Japanese
);
my $width = 5 + max map { colwidth } keys %price;
# So the Asian stuff comes out in an order that someone
# who reads those scripts won't freak out over; the
# CJK stuff will be in JIS X 0208 order that way.
my $coll = new Unicode::Collate::Locale locale => "ja";
for my $item ($coll->sort(keys %price)) {
print pad(entitle($item), $width, ".");
printf " X%.2f\n", $price{$item};
}
sub pad($$$) {
my($str, $width, $padchar) = @_;
return $str . ($padchar x ($width - colwidth($str)));
}
sub colwidth(_) {
my($str) = @_;
return Unicode::GCString->new($str)->columns;
}
sub entitle(_) {
my($str) = @_;
$str =~ s{ (?=\pL)(\S) (\S*) }
{ ucfirst($1) . lc($2) }xge;
return $str;
}
SEE ALSO¶
See these manpages, some of which are CPAN modules: perlunicode, perluniprops,
perlre, perlrecharclass, perluniintro, perlunitut, perlunifaq, PerlIO,
DB_File, DBM_Filter, DBM_Filter::utf8, Encode, Encode::Locale, Unicode::UCD,
Unicode::Normalize, Unicode::GCString, Unicode::LineBreak, Unicode::Collate,
Unicode::Collate::Locale, Unicode::Unihan, Unicode::CaseFold, Unicode::Tussle,
Lingua::JA::Romanize::Japanese, Lingua::ZH::Romanize::Pinyin,
Lingua::KO::Romanize::Hangul.
The Unicode::Tussle CPAN module includes many programs to help with working with
Unicode, including these programs to fully or partly replace standard
utilities:
tcgrep instead of
egrep,
uniquote instead of
cat -v or
hexdump,
uniwc instead of
wc,
unilook instead of
look,
unifmt instead of
fmt,
and
ucsort instead of
sort. For exploring Unicode character
names and character properties, see its
uniprops,
unichars, and
uninames programs. It also supplies these programs, all of which are
general filters that do Unicode-y things:
unititle and
unicaps;
uniwide and
uninarrow;
unisupers and
unisubs;
nfd,
nfc,
nfkd, and
nfkc; and
uc,
lc, and
tc.
Finally, see the published Unicode Standard (page numbers are from version
6.0.0), including these specific annexes and technical reports:
- X3.13 Default Case Algorithms, page 113; X4.2 Case, pages 120X122; Case
Mappings, page 166X172, especially Caseless Matching starting on page
170.
- UAX #44: Unicode Character Database
- UTS #18: Unicode Regular Expressions
- UAX #15: Unicode Normalization Forms
- UTS #10: Unicode Collation Algorithm
- UAX #29: Unicode Text Segmentation
- UAX #14: Unicode Line Breaking Algorithm
- UAX #11: East Asian Width
AUTHOR¶
Tom Christiansen <tchrist@perl.com> wrote this, with occasional kibbitzing
from Larry Wall and Jeffrey Friedl in the background.
COPYRIGHT AND LICENCE¶
Copyright X 2012 Tom Christiansen.
This program is free software; you may redistribute it and/or modify it under
the same terms as Perl itself.
Most of these examples taken from the current edition of the XCamel BookX; that
is, from the 4XX Edition of
Programming Perl, Copyright X 2012 Tom
Christiansen <et al.>, 2012-02-13 by OXReilly Media. The code itself is
freely redistributable, and you are encouraged to transplant, fold, spindle,
and mutilate any of the examples in this manpage however you please for
inclusion into your own programs without any encumbrance whatsoever.
Acknowledgement via code comment is polite but not required.
REVISION HISTORY¶
v1.0.0 X first public release, 2012-02-27