Update the libnet tests as per #11138.

[perl5.git] / lib / open.pm

diff --git a/lib/open.pm b/lib/open.pm
index 53ae308..3a08b79 100644 (file)
--- a/lib/open.pm
+++ b/lib/open.pm
@@ -2,14 +2,7 @@ package open;
 use Carp;
 $open::hint_bits = 0x20000;
 
-use vars qw(%layers @layers);
-
-# Populate hash in non-PerlIO case
-%layers = (crlf => 1, raw => 0) unless (@layers);
-
-# warn join(',',keys %layers);
-
-our $VERSION = '1.00';
+our $VERSION = '1.01';
 
 sub import {
     my ($class,@args) = @_;
@@ -24,7 +17,7 @@ sub import {
        my @val;
        foreach my $layer (split(/\s+/,$discp)) {
             $layer =~ s/^://;
-           unless(exists $layers{$layer}) {
+           unless(PerlIO::Layer::->find($layer)) {
                carp("Unknown discipline layer '$layer'");
            }
            push(@val,":$layer");
@@ -58,44 +51,48 @@ open - perl pragma to set default disciplines for input and output
 
 =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.
 
-Only the two pseudo-disciplines ":raw" and ":crlf" are currently
-available.
+When open() is given an explicit list of layers they are appended to
+the list declared using this pragma.
+
+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