Change 13743 by jhi@alpha on 2001/12/17 19:26:34
perluniintro tweaks as suggested by Jeffrey Friedl.
Affected files ...
.... //depot/perl/pod/perluniintro.pod#9 edit
Differences ...
==== //depot/perl/pod/perluniintro.pod#9 (text) ====
Index: perl/pod/perluniintro.pod
--- perl/pod/perluniintro.pod.~1~ Mon Dec 17 12:30:06 2001
+++ perl/pod/perluniintro.pod Mon Dec 17 12:30:06 2001
@@ -139,9 +139,33 @@
possible, but as soon as Unicodeness cannot be avoided, the data is
transparently upgraded to Unicode.
-The internal encoding of Unicode in Perl is UTF-8. The internal
-encoding is normally hidden, however, and one need not and should not
-worry about the internal encoding at all: it is all just characters.
+Internally, Perl currently uses either whatever the native eight-bit
+character set of the platform (for example Latin-1) or UTF-8 to encode
+Unicode strings. Specifically, if all code points in the string are
+0xFF or less, Perl uses Latin-1. Otherwise, it uses UTF-8.
+
+A user of Perl does not normally need to know nor care how Perl happens
+to encodes its internal strings, but it becomes relevant when outputting
+Unicode strings to a stream without a discipline (one with the "default
+default"). In such a case, the raw bytes used internally (the native
+character set or UTF-8, as appropriate for each string) will be used,
+and if warnings are turned on, a "Wide character" warning will be issued
+if those strings contain a character beyond 0x00FF.
+
+For example,
+
+ perl -w -e 'print "\x{DF}\n", "\x{0100}\x{DF}\n"'
+
+produces a fairly useless mixture of native bytes and UTF-8, as well
+as a warning.
+
+To output UTF-8 always, use the ":utf8" output discipline. Prepending
+
+ binmode(STDOUT, ":utf8");
+
+to this sample program ensures the output is completely UTF-8, and
+of course, removes the warning. Another way to achieve this is the
+L<encoding> pragma, discussed later in L</Legacy Encodings>.
Perl 5.8.0 will also support Unicode on EBCDIC platforms. There the
support is somewhat harder to implement since additional conversions
@@ -149,12 +173,14 @@
support won't be quite as full as in other, mainly ASCII-based,
platforms (the Unicode support will be better than in the 5.6 series,
which didn't work much at all for EBCDIC platform). On EBCDIC
-platforms the internal encoding form used is UTF-EBCDIC.
+platforms the internal encoding form used is UTF-EBCDIC instead
+of UTF-8 (the difference is that as UTF-8 is "ASCII-safe" in that
+ASCII characters encode to UTF-8 as-is, UTF-EBCDIC is "EBCDIC-safe").
=head2 Creating Unicode
-To create Unicode literals, use the C<\x{...}> notation in
-doublequoted strings:
+To create Unicode literals for code points above 0xFF, use the
+C<\x{...}> notation in doublequoted strings:
my $smiley = "\x{263a}";
End of Patch.
