3 $open::hint_bits = 0x20000;
9 sub in_locale { $^H & $locale::hint_bits }
11 sub _get_locale_encoding {
12 unless (defined $locale_encoding) {
13 # I18N::Langinfo isn't available everywhere
14 eval "use I18N::Langinfo qw(langinfo CODESET)";
16 $locale_encoding = langinfo(CODESET());
19 if (not $locale_encoding && in_locale()) {
20 if ($ENV{LC_ALL} =~ /^([^.]+)\.([^.]+)$/) {
21 ($country_language, $locale_encoding) = ($1, $2);
22 } elsif ($ENV{LANG} =~ /^([^.]+)\.([^.]+)$/) {
23 ($country_language, $locale_encoding) = ($1, $2);
25 } elsif (not $locale_encoding) {
26 if ($ENV{LC_ALL} =~ /\butf-?8\b/i ||
27 $ENV{LANG} =~ /\butf-?8\b/i) {
28 $locale_encoding = 'utf8';
30 # Could do more heuristics based on the country and language
31 # parts of LC_ALL and LANG (the parts before the dot (if any)),
32 # since we have Locale::Country and Locale::Language available.
33 # TODO: get a database of Language -> Encoding mappings
34 # (the Estonian database at http://www.eki.ee/letter/
35 # would be excellent!) --jhi
37 if (defined $locale_encoding &&
38 $locale_encoding eq 'euc' &&
39 defined $country_language) {
40 if ($country_language =~ /^ja_JP|japan(?:ese)?$/i) {
41 $locale_encoding = 'euc-jp';
42 } elsif ($country_language =~ /^ko_KR|korean?$/i) {
43 $locale_encoding = 'euc-kr';
44 } elsif ($country_language =~ /^zh_TW|taiwan(?:ese)?$/i) {
45 $locale_encoding = 'euc-tw';
47 croak "Locale encoding 'euc' too ambiguous"
48 if $locale_encoding eq 'euc';
54 my ($class,@args) = @_;
55 croak("`use open' needs explicit list of disciplines") unless @args;
56 $^H |= $open::hint_bits;
57 my ($in,$out) = split(/\0/,(${^OPEN} || "\0"), -1);
59 my $type = shift(@args);
61 if ($type =~ /^:?(utf8|locale|encoding\(.+\))$/) {
68 foreach my $layer (split(/\s+/,$dscp)) {
70 if ($layer eq 'locale') {
72 _get_locale_encoding()
73 unless defined $locale_encoding;
74 croak "Cannot figure out an encoding to use"
75 unless defined $locale_encoding;
76 if ($locale_encoding =~ /^utf-?8$/i) {
79 $layer = "encoding($locale_encoding)";
82 unless(PerlIO::Layer::->find($layer)) {
83 carp("Unknown discipline layer '$layer'");
87 if ($layer =~ /^(crlf|raw)$/) {
88 $^H{"open_$type"} = $layer;
91 # print "# type = $type, val = @val\n";
95 elsif ($type eq 'OUT') {
96 $out = join(' ',@val);
98 elsif ($type eq 'IO') {
99 $in = $out = join(' ',@val);
102 croak "Unknown discipline class '$type'";
105 ${^OPEN} = join("\0",$in,$out);
113 open - perl pragma to set default disciplines for input and output
117 use open IN => ":crlf", OUT => ":raw";
118 use open OUT => ':utf8';
119 use open IO => ":encoding(iso-8859-7)";
121 use open IO => ':locale';
125 use open ':encoding(iso-8859-7)';
129 Full-fledged support for I/O disciplines is now implemented provided
130 Perl is configured to use PerlIO as its IO system (which is now the
133 The C<open> pragma serves as one of the interfaces to declare default
134 "layers" (aka disciplines) for all I/O.
136 The C<open> pragma is used to declare one or more default layers for
137 I/O operations. Any open(), readpipe() (aka qx//) and similar
138 operators found within the lexical scope of this pragma will use the
141 With the C<IN> subpragma you can declare the default layers
142 of input sterams, and with the C<OUT> subpragma you can declare
143 the default layers of output streams. With the C<IO> subpragma
144 you can control both input and output streams simultaneously.
146 If you have a legacy encoding, you can use the C<:encoding(...)> tag.
148 if you want to set your encoding disciplines based on your
149 locale environment variables, you can use the C<:locale> tag.
152 $ENV{LANG} = 'ru_RU.KOI8-R';
153 # the :locale will probe the locale environment variables like LANG
154 use open OUT => ':locale';
156 print O chr(0x430); # Unicode CYRILLIC SMALL LETTER A = KOI8-R 0xc1
159 printf "%#x\n", ord(<I>), "\n"; # this should print 0xc1
165 use open IO => ':utf8';
170 use open IO => ':locale';
174 use open ':encoding(iso-8859-7)';
175 use open IO => ':encoding(iso-8859-7)';
177 When open() is given an explicit list of layers they are appended to
178 the list declared using this pragma.
180 Directory handles may also support disciplines in future.
182 =head1 NONPERLIO FUNCTIONALITY
184 If Perl is not built to use PerlIO as its IO system then only the two
185 pseudo-disciplines ":raw" and ":crlf" are available.
187 The ":raw" discipline corresponds to "binary mode" and the ":crlf"
188 discipline corresponds to "text mode" on platforms that distinguish
189 between the two modes when opening files (which is many DOS-like
190 platforms, including Windows). These two disciplines are no-ops on
191 platforms where binmode() is a no-op, but perform their functions
192 everywhere if PerlIO is enabled.
194 =head1 IMPLEMENTATION DETAILS
196 There is a class method in C<PerlIO::Layer> C<find> which is
197 implemented as XS code. It is called by C<import> to validate the
200 PerlIO::Layer::->find("perlio")
202 The return value (if defined) is a Perl object, of class
203 C<PerlIO::Layer> which is created by the C code in F<perlio.c>. As
204 yet there is nothing useful you can do with the object at the perl
209 L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>, L<PerlIO>,