3 $open::hint_bits = 0x20000;
9 sub in_locale { $^H & $locale::hint_bits }
11 sub _get_locale_encoding {
12 unless (defined $locale_encoding) {
13 eval { use I18N::Langinfo qw(langinfo CODESET) };
15 $locale_encoding = langinfo(CODESET);
18 if (not $locale_encoding && in_locale()) {
19 if ($ENV{LC_ALL} =~ /^([^.]+)\.([^.]+)$/) {
20 ($country_language, $locale_encoding) = ($1, $2);
21 } elsif ($ENV{LANG} =~ /^([^.]+)\.([^.]+)$/) {
22 ($country_language, $locale_encoding) = ($1, $2);
25 # Could do heuristics based on the country and language
26 # parts of LC_ALL and LANG (the parts before the dot (if any)),
27 # since we have Locale::Country and Locale::Language available.
28 # TODO: get a database of Language -> Encoding mappings
29 # (the Estonian database would be excellent!)
32 if (defined $locale_encoding &&
33 $locale_encoding eq 'euc' &&
34 defined $country_language) {
35 if ($country_language =~ /^ja_JP|japan(?:ese)$/i) {
36 $locale_encoding = 'eucjp';
37 } elsif ($country_language =~ /^ko_KR|korea(?:n)$/i) {
38 $locale_encoding = 'euckr';
39 } elsif ($country_language =~ /^zh_TW|taiwan(?:ese)$/i) {
40 $locale_encoding = 'euctw';
42 croak "Locale encoding 'euc' too ambiguous"
43 if $locale_encoding eq 'euc';
49 my ($class,@args) = @_;
50 croak("`use open' needs explicit list of disciplines") unless @args;
51 $^H |= $open::hint_bits;
52 my ($in,$out) = split(/\0/,(${^OPEN} || '\0'));
53 my @in = split(/\s+/,$in);
54 my @out = split(/\s+/,$out);
56 my $type = shift(@args);
57 my $discp = shift(@args);
59 foreach my $layer (split(/\s+/,$discp)) {
61 if ($layer eq 'locale') {
63 _get_locale_encoding()
64 unless defined $locale_encoding;
65 croak "Cannot figure out an encoding to use"
66 unless defined $locale_encoding;
67 if ($locale_encoding =~ /^utf-?8$/i) {
70 $layer = "encoding($locale_encoding)";
73 unless(PerlIO::Layer::->find($layer)) {
74 carp("Unknown discipline layer '$layer'");
77 if ($layer =~ /^(crlf|raw)$/) {
78 $^H{"open_$type"} = $layer;
84 elsif ($type eq 'OUT') {
85 $out = join(' ',@val);
88 croak "Unknown discipline class '$type'";
91 ${^OPEN} = join('\0',$in,$out);
99 open - perl pragma to set default disciplines for input and output
103 use open IN => ":crlf", OUT => ":raw";
107 Full-fledged support for I/O disciplines is now implemented provided
108 Perl is configured to use PerlIO as its IO system (which is now the
111 The C<open> pragma serves as one of the interfaces to declare default
112 "layers" (aka disciplines) for all I/O.
114 The C<open> pragma is used to declare one or more default layers for
115 I/O operations. Any open(), readpipe() (aka qx//) and similar
116 operators found within the lexical scope of this pragma will use the
119 When open() is given an explicit list of layers they are appended to
120 the list declared using this pragma.
122 Directory handles may also support disciplines in future.
124 =head1 NONPERLIO FUNCTIONALITY
126 If Perl is not built to use PerlIO as its IO system then only the two
127 pseudo-disciplines ":raw" and ":crlf" are available.
129 The ":raw" discipline corresponds to "binary mode" and the ":crlf"
130 discipline corresponds to "text mode" on platforms that distinguish
131 between the two modes when opening files (which is many DOS-like
132 platforms, including Windows). These two disciplines are no-ops on
133 platforms where binmode() is a no-op, but perform their functions
134 everywhere if PerlIO is enabled.
136 =head1 IMPLEMENTATION DETAILS
138 There is a class method in C<PerlIO::Layer> C<find> which is implemented as XS code.
139 It is called by C<import> to validate the layers:
141 PerlIO::Layer::->find("perlio")
143 The return value (if defined) is a Perl object, of class C<PerlIO::Layer> which is
144 created by the C code in F<perlio.c>. As yet there is nothing useful you can do with the
145 object at the perl level.
149 L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>, L<PerlIO>