support binmode(F,":crlf") and use open IN => ":raw", OUT => ":crlf"

semantics; the pragma sets defaults for both open() and qx//

p4raw-id: //depot/perl@5628

1 files changed, 55 insertions, 15 deletions

diff --git a/lib/open.pm b/lib/open.pm
index da8a04453c..8f5c13833b 100644
--- a/lib/open.pm
+++ b/lib/open.pm
@@ -1,4 +1,27 @@
 package open;
+$open::hint_bits = 0x20000;
+
+sub import {
+    shift;
+    die "`use open' needs explicit list of disciplines" unless @_;
+    $^H |= $open::hint_bits;
+    while (@_) {
+	my $type = shift;
+	if ($type =~ /^(IN|OUT)\z/s) {
+	    my $discp = shift;
+	    unless ($discp =~ /^\s*:(raw|crlf)\s*\z/s) {
+		die "Unknown discipline '$discp'";
+	    }
+	    $^H{"open_$type"} = $discp;
+	}
+	else {
+	    die "Unknown discipline class '$type'";
+	}
+    }
+}
+
+1;
+__END__
 
 =head1 NAME
 
@@ -6,31 +29,48 @@ open - perl pragma to set default disciplines for input and output
 
 =head1 SYNOPSIS
 
-    use open IN => ":any", OUT => ":utf8";	# unimplemented
+    use open IN => ":crlf", OUT => ":raw";
 
 =head1 DESCRIPTION
 
-NOTE: This pragma is not yet implemented.
-
 The open pragma is used to declare one or more default disciplines for
-I/O operations.  Any constructors for file, socket, pipe, or directory
-handles found within the lexical scope of this pragma will use the
-declared default.
+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
+not influenced by this pragma.
+
+Only the two pseudo-disciplines ":raw" and ":crlf" are currently
+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.
 
-Handle constructors that are called with an explicit set of disciplines
-are not influenced by the declared defaults.
+=head1 UNIMPLEMENTED FUNCTIONALITY
 
-The default disciplines so declared are available by the special
-discipline name ":def", and can be used within handle constructors
-that allow disciplines to be specified.  This makes it possible to
-stack new disciplines over the default ones.
+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.
+
+In future, any default disciplines declared by this pragma will be
+available by the special discipline name ":def", 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.
 
     open FH, "<:para :def", $file or die "can't open $file: $!";
 
+Socket and directory handles will also support disciplines in
+future.
+
+Full support for I/O disciplines will enable all of the supported
+disciplines to work on all platforms.
+
 =head1 SEE ALSO
 
-L<perlunicode>, L<perlfunc/"open">
+L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>
 
 =cut
-
-1;