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);
29 # Could do heuristics based on the country and language
30 # parts of LC_ALL and LANG (the parts before the dot (if any)),
31 # since we have Locale::Country and Locale::Language available.
32 # TODO: get a database of Language -> Encoding mappings
33 # (the Estonian database at http://www.eki.ee/letter/
34 # would be excellent!) --jhi
36 if (defined $locale_encoding &&
37 $locale_encoding eq 'euc' &&
38 defined $country_language) {
39 if ($country_language =~ /^ja_JP|japan(?:ese)?$/i) {
40 $locale_encoding = 'eucjp';
41 } elsif ($country_language =~ /^ko_KR|korean?$/i) {
42 $locale_encoding = 'euckr';
43 } elsif ($country_language =~ /^zh_TW|taiwan(?:ese)?$/i) {
44 $locale_encoding = 'euctw';
46 croak "Locale encoding 'euc' too ambiguous"
47 if $locale_encoding eq 'euc';
53 my ($class,@args) = @_;
54 croak("`use open' needs explicit list of disciplines") unless @args;
55 $^H |= $open::hint_bits;
56 my ($in,$out) = split(/\0/,(${^OPEN} || "\0"), -1);
58 my $type = shift(@args);
59 my $discp = shift(@args);
61 foreach my $layer (split(/\s+/,$discp)) {
63 if ($layer eq 'locale') {
65 _get_locale_encoding()
66 unless defined $locale_encoding;
67 croak "Cannot figure out an encoding to use"
68 unless defined $locale_encoding;
69 if ($locale_encoding =~ /^utf-?8$/i) {
72 $layer = "encoding($locale_encoding)";
75 unless(PerlIO::Layer::->find($layer)) {
76 carp("Unknown discipline layer '$layer'");
80 if ($layer =~ /^(crlf|raw)$/) {
81 $^H{"open_$type"} = $layer;
84 # print "# type = $type, val = @val\n";
88 elsif ($type eq 'OUT') {
89 $out = join(' ',@val);
91 elsif ($type eq 'INOUT') {
92 $in = $out = join(' ',@val);
95 croak "Unknown discipline class '$type'";
98 ${^OPEN} = join('\0',$in,$out);
106 open - perl pragma to set default disciplines for input and output
110 use open IN => ":crlf", OUT => ":raw";
111 use open INOUT => ":utf8";
115 Full-fledged support for I/O disciplines is now implemented provided
116 Perl is configured to use PerlIO as its IO system (which is now the
119 The C<open> pragma serves as one of the interfaces to declare default
120 "layers" (aka disciplines) for all I/O.
122 The C<open> pragma is used to declare one or more default layers for
123 I/O operations. Any open(), readpipe() (aka qx//) and similar
124 operators found within the lexical scope of this pragma will use the
127 When open() is given an explicit list of layers they are appended to
128 the list declared using this pragma.
130 Directory handles may also support disciplines in future.
132 =head1 NONPERLIO FUNCTIONALITY
134 If Perl is not built to use PerlIO as its IO system then only the two
135 pseudo-disciplines ":raw" and ":crlf" are available.
137 The ":raw" discipline corresponds to "binary mode" and the ":crlf"
138 discipline corresponds to "text mode" on platforms that distinguish
139 between the two modes when opening files (which is many DOS-like
140 platforms, including Windows). These two disciplines are no-ops on
141 platforms where binmode() is a no-op, but perform their functions
142 everywhere if PerlIO is enabled.
144 =head1 IMPLEMENTATION DETAILS
146 There is a class method in C<PerlIO::Layer> C<find> which is
147 implemented as XS code. It is called by C<import> to validate the
150 PerlIO::Layer::->find("perlio")
152 The return value (if defined) is a Perl object, of class
153 C<PerlIO::Layer> which is created by the C code in F<perlio.c>. As
154 yet there is nothing useful you can do with the object at the perl
159 L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>, L<PerlIO>