use Carp;
$open::hint_bits = 0x20000;
-use vars qw(%layers @layers);
-
-# Populate hash in non-PerlIO case
-%layers = (crlf => 1, raw => 0) unless (@layers);
-
-our $VERSION = '1.00';
+our $VERSION = '1.01';
sub import {
- shift;
- die "`use open' needs explicit list of disciplines" unless @_;
+ my ($class,@args) = @_;
+ croak("`use open' needs explicit list of disciplines") unless @args;
$^H |= $open::hint_bits;
my ($in,$out) = split(/\0/,(${^OPEN} || '\0'));
my @in = split(/\s+/,$in);
my @out = split(/\s+/,$out);
- while (@_) {
- my $type = shift;
- my $discp = shift;
+ while (@args) {
+ my $type = shift(@args);
+ my $discp = shift(@args);
my @val;
- foreach my $layer (split(/\s+:?/,$discp)) {
- unless(exists $layers{$layer}) {
- croak "Unknown discipline layer '$layer'";
+ foreach my $layer (split(/\s+/,$discp)) {
+ $layer =~ s/^://;
+ unless(PerlIO::Layer::->find($layer)) {
+ carp("Unknown discipline layer '$layer'");
}
push(@val,":$layer");
if ($layer =~ /^(crlf|raw)$/) {
=head1 DESCRIPTION
-The open pragma is used to declare one or more default disciplines for
-I/O operations. Any open() and readpipe() (aka qx//) operators found
-within the lexical scope of this pragma will use the declared defaults.
-Neither open() with an explicit set of disciplines, nor sysopen() are
-influenced by this pragma.
+Full-fledged support for I/O disciplines is now implemented provided
+Perl is configured to use PerlIO as its IO system (which is now the
+default).
+
+The C<open> pragma serves as one of the interfaces to declare default
+"layers" (aka disciplines) for all I/O.
+
+The C<open> pragma is used to declare one or more default layers for
+I/O operations. Any open(), readpipe() (aka qx//) and similar
+operators found within the lexical scope of this pragma will use the
+declared defaults.
+
+When open() is given an explicit list of layers they are appended to
+the list declared using this pragma.
-Only the two pseudo-disciplines ":raw" and ":crlf" are currently
-available.
+Directory handles may also support disciplines in future.
+
+=head1 NONPERLIO FUNCTIONALITY
+
+If Perl is not built to use PerlIO as its IO system then only the two
+pseudo-disciplines ":raw" and ":crlf" are available.
The ":raw" discipline corresponds to "binary mode" and the ":crlf"
discipline corresponds to "text mode" on platforms that distinguish
between the two modes when opening files (which is many DOS-like
-platforms, including Windows). These two disciplines are currently
-no-ops on platforms where binmode() is a no-op, but will be
-supported everywhere in future.
-
-=head1 UNIMPLEMENTED FUNCTIONALITY
-
-Full-fledged support for I/O disciplines is currently unimplemented.
-When they are eventually supported, this pragma will serve as one of
-the interfaces to declare default disciplines for all I/O.
+platforms, including Windows). These two disciplines are no-ops on
+platforms where binmode() is a no-op, but perform their functions
+everywhere if PerlIO is enabled.
-In future, any default disciplines declared by this pragma will be
-available by the special discipline name ":DEFAULT", and could be used
-within handle constructors that allow disciplines to be specified.
-This would make it possible to stack new disciplines over the default
-ones.
+=head1 IMPLEMENTATION DETAILS
- open FH, "<:para :DEFAULT", $file or die "can't open $file: $!";
+There is a class method in C<PerlIO::Layer> C<find> which is implemented as XS code.
+It is called by C<import> to validate the layers:
-Socket and directory handles will also support disciplines in
-future.
+ PerlIO::Layer::->find("perlio")
-Full support for I/O disciplines will enable all of the supported
-disciplines to work on all platforms.
+The return value (if defined) is a Perl object, of class C<PerlIO::Layer> which is
+created by the C code in F<perlio.c>. As yet there is nothing useful you can do with the
+object at the perl level.
=head1 SEE ALSO
-L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>
+L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>, L<PerlIO>
=cut