Make hv_notallowed a static as suggested by Nicholas Clark;

[perl5.git] / lib / PerlIO.pm

diff --git a/lib/PerlIO.pm b/lib/PerlIO.pm
index 04cd4cf..bb678a6 100644 (file)
--- a/lib/PerlIO.pm
+++ b/lib/PerlIO.pm
@@ -1,5 +1,7 @@
 package PerlIO;
 
+our $VERSION = '1.00';
+
 # Map layer name to package that defines it
 my %alias = (encoding => 'Encode');
 
@@ -39,8 +41,8 @@ PerlIO - On demand loader for PerlIO layers and root of PerlIO::* name space
 
 =head1 DESCRIPTION
 
-When an undefined layer 'foo' is encountered in an C<open> or C<binmode> layer
-specification then C code performs the equivalent of:
+When an undefined layer 'foo' is encountered in an C<open> or
+C<binmode> layer specification then C code performs the equivalent of:
 
   use PerlIO 'foo';
 
@@ -48,8 +50,8 @@ The perl code in PerlIO.pm then attempts to locate a layer by doing
 
   require PerlIO::foo;
 
-Otherwise the C<PerlIO> package is a place holder for additional PerLIO related
-functions.
+Otherwise the C<PerlIO> package is a place holder for additional
+PerlIO related functions.
 
 The following layers are currently defined:
 
@@ -61,60 +63,74 @@ Low level layer which calls C<read>, C<write> and C<lseek> etc.
 
 =item stdio
 
-Layer which calls C<fread>, C<fwrite> and C<fseek>/C<ftell> etc.
-Note that as this is "real" stdio it will ignore any layers beneath it and
+Layer which calls C<fread>, C<fwrite> and C<fseek>/C<ftell> etc.  Note
+that as this is "real" stdio it will ignore any layers beneath it and
 got straight to the operating system via the C library as usual.
 
 =item perlio
 
-This is a re-implementation of "stdio-like" buffering written as a PerlIO "layer".
-As such it will call whatever layer is below it for its operations.
+This is a re-implementation of "stdio-like" buffering written as a
+PerlIO "layer".  As such it will call whatever layer is below it for
+its operations.
 
 =item crlf
 
-A layer which does CRLF to "\n" translation distinguishing "text" and "binary"
-files in the manner of MS-DOS and similar operating systems.
+A layer which does CRLF to "\n" translation distinguishing "text" and
+"binary" files in the manner of MS-DOS and similar operating systems.
 
 =item utf8
 
-Declares that the stream accepts perl's internal encoding of characters.
-(Which really is UTF-8 on ASCII machines, but is UTF-EBCDIC on EBCDIC machines.)
-This allows any character perl can represent to be read from or written to the
-stream. The UTF-X encoding is chosen to render simple text parts (i.e.
-non-accented letters, digits and common punctuation) human readable in the
-encoded file.
+Declares that the stream accepts perl's internal encoding of
+characters.  (Which really is UTF-8 on ASCII machines, but is
+UTF-EBCDIC on EBCDIC machines.)  This allows any character perl can
+represent to be read from or written to the stream. The UTF-X encoding
+is chosen to render simple text parts (i.e.  non-accented letters,
+digits and common punctuation) human readable in the encoded file.
+
+Here is how to write your native data out using UTF-8 (or UTF-EBCDIC)
+and then read it back in.
+
+       open(F, ">:utf8", "data.utf");
+       print F $out;
+       close(F);
+
+       open(F, "<:utf8", "data.utf");
+       $in = <F>;
+       close(F);
 
 =item raw
 
-A pseudo-layer which performs two functions (which is messy, but necessary to
-maintain compatibility with non-PerLIO builds of perl and they way things
-have been documented elsewhere).
+A pseudo-layer which performs two functions (which is messy, but
+necessary to maintain compatibility with non-PerlIO builds of Perl
+and their way things have been documented elsewhere).
 
-Firstly it forces the file handle to be considered binary at that point
-in the layer stack,
+Firstly it forces the file handle to be considered binary at that
+point in the layer stack,
 
-Secondly in prevents the IO system seaching back before it in the layer specification.
-Thus:
+Secondly in prevents the IO system seaching back before it in the
+layer specification.  Thus:
 
-    open($fh,":raw:perlio"),...)
+    open($fh,":raw:perlio",...)
 
-Forces the use of C<perlio> layer even if the platform default, or C<use open> default
-is something else (such as ":encoding(iso-8859-7)" ) which would interfere with
+Forces the use of C<perlio> layer even if the platform default, or
+C<use open> default is something else (such as ":encoding(iso-8859-7)")
+(the C<:encoding> requires C<use Encode>) which would interfere with
 binary nature of the stream.
 
 =back
 
 =head2 Defaults and how to override them
 
-If the platform is MS-DOS like and normally does CRLF to "\n" translation
-for text files then the default layers are :
+If the platform is MS-DOS like and normally does CRLF to "\n"
+translation for text files then the default layers are :
 
   unix crlf
 
-(The low level "unix" layer may be replaced by a platform specific low level layer.)
+(The low level "unix" layer may be replaced by a platform specific low
+level layer.)
 
-Otherwise if C<Configure> found out how to do "fast" IO using system's stdio, then
-the default layers are :
+Otherwise if C<Configure> found out how to do "fast" IO using system's
+stdio, then the default layers are :
 
   unix stdio
 
@@ -124,9 +140,10 @@ Otherwise the default layers are
 
 These defaults may change once perlio has been better tested and tuned.
 
-The default can be overridden by setting the environment variable PERLIO
-to a space separated list of layers (unix or platform low level layer is
-always pushed first).
+The default can be overridden by setting the environment variable
+PERLIO to a space separated list of layers (unix or platform low level
+layer is always pushed first).
+
 This can be used to see the effect of/bugs in the various layers e.g.
 
   cd .../perl/t
@@ -139,7 +156,7 @@ Nick Ing-Simmons E<lt>nick@ing-simmons.netE<gt>
 
 =head1 SEE ALSO
 
-L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>, L<open>
+L<perlfunc/"binmode">, L<perlfunc/"open">, L<perlunicode>, L<Encode>
 
 =cut