Integrate mainline some more

[p5sagit/p5-mst-13.2.git] / pod / perluniintro.pod

diff --git a/pod/perluniintro.pod b/pod/perluniintro.pod
index cdd0b40..7714d13 100644 (file)
--- a/pod/perluniintro.pod
+++ b/pod/perluniintro.pod
@@ -170,11 +170,12 @@ At run-time you can use C<chr()>:
 
 Naturally, C<ord()> will do the reverse: turn a character to a code point.
 
-Note that C<\x..>, C<\x{..}> and C<chr(...)> for arguments less than
-0x100 (decimal 256) will generate an eight-bit character for backward
-compatibility with older Perls.  For arguments of 0x100 or more,
-Unicode will always be produced.  If you want UTF-8 always, use
-C<pack("U", ...)> instead of C<\x..>, C<\x{..}>, or C<chr()>.
+Note that C<\x..> (no C<{}> and only two hexadecimal digits), C<\x{...}>
+and C<chr(...)> for arguments less than 0x100 (decimal 256) will
+generate an eight-bit character for backward compatibility with older
+Perls.  For arguments of 0x100 or more, Unicode will always be
+produced.  If you want UTF-8 always, use C<pack("U", ...)> instead of
+C<\x..>, C<\x{...}>, or C<chr()>.
 
 You can also use the C<charnames> pragma to invoke characters
 by name in doublequoted strings:
@@ -187,6 +188,10 @@ characters:
 
    my $georgian_an  = pack("U", 0x10a0);
 
+Note that both C<\x{...}> and C<\N{...}> are compile-time string
+constants: you cannot use variables in them.  if you want similar
+run-time functionality, use C<chr()> and C<charnames::vianame()>.
+
 =head2 Handling Unicode
 
 Handling Unicode is for the most part transparent: just use the
@@ -236,11 +241,19 @@ for doing conversions between those encodings:
 
 Normally writing out Unicode data
 
-    print chr(0x100), "\n";
+    print FH chr(0x100), "\n";
+
+will print out the raw UTF-8 bytes, but you will get a warning
+out of that if you use C<-w> or C<use warnings>.  To avoid the
+warning open the stream explicitly in UTF-8:
+
+    open FH, ">:utf8", "file";
 
-will print out the raw UTF-8 bytes.
+and on already open streams use C<binmode()>:
 
-But reading in correctly formed UTF-8 data will not magically turn
+    binmode(STDOUT, ":utf8");
+
+Reading in correctly formed UTF-8 data will not magically turn
 the data into Unicode in Perl's eyes.
 
 You can use either the C<':utf8'> I/O discipline when opening files
@@ -251,11 +264,11 @@ You can use either the C<':utf8'> I/O discipline when opening files
 The I/O disciplines can also be specified more flexibly with
 the C<open> pragma; see L<open>:
 
-    use open ':utf8'; # input and output will be UTF-8
-    open X, ">utf8";
-    print X chr(0x100), "\n"; # this would have been UTF-8 without the pragma
+    use open ':utf8'; # input and output default discipline will be UTF-8
+    open X, ">file";
+    print X chr(0x100), "\n";
     close X;
-    open Y, "<utf8";
+    open Y, "<file";
     printf "%#x\n", ord(<Y>); # this should print 0x100
     close Y;
 
@@ -329,7 +342,8 @@ by repeatedly encoding it in UTF-8:
     close F;
 
 If you run this code twice, the contents of the F<file> will be twice
-UTF-8 encoded.  A C<use open ':utf8'> would have avoided the bug.
+UTF-8 encoded.  A C<use open ':utf8'> would have avoided the bug, or
+explicitly opening also the F<file> for input as UTF-8.
 
 =head2 Special Cases
 
@@ -378,8 +392,8 @@ String Equivalence
 The question of string equivalence turns somewhat complicated
 in Unicode: what do you mean by equal?
 
-    Is C<LATIN CAPITAL LETTER A WITH ACUTE> equal to
-    C<LATIN CAPITAL LETTER A>?
+(Is C<LATIN CAPITAL LETTER A WITH ACUTE> equal to
+C<LATIN CAPITAL LETTER A>?)
 
 The short answer is that by default Perl compares equivalence
 (C<eq>, C<ne>) based only on code points of the characters.
@@ -404,8 +418,8 @@ String Collation
 People like to see their strings nicely sorted, or as Unicode
 parlance goes, collated.  But again, what do you mean by collate?
 
-    Does C<LATIN CAPITAL LETTER A WITH ACUTE> come before or after
-    C<LATIN CAPITAL LETTER A WITH GRAVE>?
+(Does C<LATIN CAPITAL LETTER A WITH ACUTE> come before or after
+C<LATIN CAPITAL LETTER A WITH GRAVE>?)
 
 The short answer is that by default Perl compares strings (C<lt>,
 C<le>, C<cmp>, C<ge>, C<gt>) based only on the code points of the
@@ -671,6 +685,14 @@ the C<Unicode::UCD> module.
 
 =back
 
+=head1 UNICODE IN OLDER PERLS
+
+If you cannot upgrade your Perl to 5.8.0 or later, you can still
+do some Unicode processing by using the modules C<Unicode::String>,
+C<Unicode::Map8>, and C<Unicode::Map>, available from CPAN.
+If you have the GNU recode installed, you can also use the
+Perl frontend C<Convert::Recode> for character conversions.
+
 =head1 SEE ALSO
 
 L<perlunicode>, L<Encode>, L<encoding>, L<open>, L<utf8>, L<bytes>,