3 $open::hint_bits = 0x20000;
9 sub in_locale { $^H & $locale::hint_bits }
11 sub _get_locale_encoding {
12 unless (defined $locale_encoding) {
14 # I18N::Langinfo isn't available everywhere
15 require I18N::Langinfo;
16 I18N::Langinfo->import('langinfo', 'CODESET');
19 $locale_encoding = langinfo(CODESET());
22 if (not $locale_encoding && in_locale()) {
23 if ($ENV{LC_ALL} =~ /^([^.]+)\.([^.]+)$/) {
24 ($country_language, $locale_encoding) = ($1, $2);
25 } elsif ($ENV{LANG} =~ /^([^.]+)\.([^.]+)$/) {
26 ($country_language, $locale_encoding) = ($1, $2);
28 } elsif (not $locale_encoding) {
29 if ($ENV{LC_ALL} =~ /\butf-?8\b/i ||
30 $ENV{LANG} =~ /\butf-?8\b/i) {
31 $locale_encoding = 'utf8';
33 # Could do more heuristics based on the country and language
34 # parts of LC_ALL and LANG (the parts before the dot (if any)),
35 # since we have Locale::Country and Locale::Language available.
36 # TODO: get a database of Language -> Encoding mappings
37 # (the Estonian database at http://www.eki.ee/letter/
38 # would be excellent!) --jhi
40 if (defined $locale_encoding &&
41 $locale_encoding eq 'euc' &&
42 defined $country_language) {
43 if ($country_language =~ /^ja_JP|japan(?:ese)?$/i) {
44 $locale_encoding = 'euc-jp';
45 } elsif ($country_language =~ /^ko_KR|korean?$/i) {
46 $locale_encoding = 'euc-kr';
47 } elsif ($country_language =~ /^zh_TW|taiwan(?:ese)?$/i) {
48 $locale_encoding = 'euc-tw';
50 croak "Locale encoding 'euc' too ambiguous"
51 if $locale_encoding eq 'euc';
57 my ($class,@args) = @_;
58 croak("`use open' needs explicit list of disciplines") unless @args;
59 $^H |= $open::hint_bits;
60 my ($in,$out) = split(/\0/,(${^OPEN} || "\0"), -1);
62 my $type = shift(@args);
64 if ($type =~ /^:?(utf8|locale|encoding\(.+\))$/) {
71 foreach my $layer (split(/\s+/,$dscp)) {
73 if ($layer eq 'locale') {
75 _get_locale_encoding()
76 unless defined $locale_encoding;
77 croak "Cannot figure out an encoding to use"
78 unless defined $locale_encoding;
79 if ($locale_encoding =~ /^utf-?8$/i) {
82 $layer = "encoding($locale_encoding)";
85 unless(PerlIO::Layer::->find($layer)) {
86 carp("Unknown discipline layer '$layer'");
90 if ($layer =~ /^(crlf|raw)$/) {
91 $^H{"open_$type"} = $layer;
94 # print "# type = $type, val = @val\n";
98 elsif ($type eq 'OUT') {
99 $out = join(' ',@val);
101 elsif ($type eq 'IO') {
102 $in = $out = join(' ',@val);
105 croak "Unknown discipline class '$type'";
108 ${^OPEN} = join("\0",$in,$out);
116 open - perl pragma to set default disciplines for input and output
120 use open IN => ":crlf", OUT => ":raw";
121 use open OUT => ':utf8';
122 use open IO => ":encoding(iso-8859-7)";
124 use open IO => ':locale';
128 use open ':encoding(iso-8859-7)';
132 Full-fledged support for I/O disciplines is now implemented provided
133 Perl is configured to use PerlIO as its IO system (which is now the
136 The C<open> pragma serves as one of the interfaces to declare default
137 "layers" (aka disciplines) for all I/O.
139 The C<open> pragma is used to declare one or more default layers for
140 I/O operations. Any open(), readpipe() (aka qx//) and similar
141 operators found within the lexical scope of this pragma will use the
144 With the C<IN> subpragma you can declare the default layers
145 of input sterams, and with the C<OUT> subpragma you can declare
146 the default layers of output streams. With the C<IO> subpragma
147 you can control both input and output streams simultaneously.
149 If you have a legacy encoding, you can use the C<:encoding(...)> tag.
151 if you want to set your encoding disciplines based on your
152 locale environment variables, you can use the C<:locale> tag.
155 $ENV{LANG} = 'ru_RU.KOI8-R';
158 print O chr(0x430); # Unicode CYRILLIC SMALL LETTER A = KOI8-R 0xC1
161 printf "%#x\n", ord(<I>), "\n"; # this should print 0xC1
167 use open IO => ':utf8';
172 use open IO => ':locale';
176 use open ':encoding(iso-8859-7)';
177 use open IO => ':encoding(iso-8859-7)';
179 When open() is given an explicit list of layers they are appended to
180 the list declared using this pragma.
182 Directory handles may also support disciplines in future.
184 =head1 NONPERLIO FUNCTIONALITY
186 If Perl is not built to use PerlIO as its IO system then only the two
187 pseudo-disciplines ":raw" and ":crlf" are available.
189 The ":raw" discipline corresponds to "binary mode" and the ":crlf"
190 discipline corresponds to "text mode" on platforms that distinguish
191 between the two modes when opening files (which is many DOS-like
192 platforms, including Windows). These two disciplines are no-ops on
193 platforms where binmode() is a no-op, but perform their functions
194 everywhere if PerlIO is enabled.
196 =head1 IMPLEMENTATION DETAILS
198 There is a class method in C<PerlIO::Layer> C<find> which is
199 implemented as XS code. It is called by C<import> to validate the
202 PerlIO::Layer::->find("perlio")
204 The return value (if defined) is a Perl object, of class
205 C<PerlIO::Layer> which is created by the C code in F<perlio.c>. As
206 yet there is nothing useful you can do with the object at the perl
211 L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>, L<PerlIO>,