diff options
Diffstat (limited to 'pod')
| -rw-r--r-- | pod/perlcheat.pod | 2 | ||||
| -rw-r--r-- | pod/perlfunc.pod | 30 | ||||
| -rw-r--r-- | pod/perlopentut.pod | 2 | ||||
| -rw-r--r-- | pod/perlrun.pod | 6 | ||||
| -rw-r--r-- | pod/perlunicode.pod | 2 | ||||
| -rw-r--r-- | pod/perlunifaq.pod | 155 | ||||
| -rw-r--r-- | pod/perluniintro.pod | 21 | ||||
| -rw-r--r-- | pod/perlunitut.pod | 2 |
8 files changed, 137 insertions, 83 deletions
diff --git a/pod/perlcheat.pod b/pod/perlcheat.pod index 440b35991b..07853a8056 100644 --- a/pod/perlcheat.pod +++ b/pod/perlcheat.pod @@ -84,7 +84,7 @@ Perl 6 version to show that Perl will stay Perl. =head1 AUTHOR -Juerd Waalboer <juerd@cpan.org>, with the help of many Perl Monks. +Juerd Waalboer <#####@juerd.nl>, with the help of many Perl Monks. =head1 SEE ALSO diff --git a/pod/perlfunc.pod b/pod/perlfunc.pod index f954aa227a..8a845572d0 100644 --- a/pod/perlfunc.pod +++ b/pod/perlfunc.pod @@ -4345,10 +4345,10 @@ See L<perlipc/"UDP: Message Passing"> for examples. Note the I<characters>: depending on the status of the socket, either (8-bit) bytes or characters are received. By default all sockets operate on bytes, but for example if the socket has been changed using -binmode() to operate with the C<:utf8> I/O layer (see the C<open> -pragma, L<open>), the I/O will operate on UTF-8 encoded Unicode -characters, not bytes. Similarly for the C<:encoding> pragma: -in that case pretty much any characters can be read. +binmode() to operate with the C<:encoding(utf8)> I/O layer (see the +C<open> pragma, L<open>), the I/O will operate on UTF-8 encoded Unicode +characters, not bytes. Similarly for the C<:encoding> pragma: in that +case pretty much any characters can be read. =item redo LABEL X<redo> @@ -4784,7 +4784,7 @@ of the file) from the Fcntl module. Returns C<1> upon success, C<0> otherwise. Note the I<in bytes>: even if the filehandle has been set to -operate on characters (for example by using the C<:utf8> open +operate on characters (for example by using the C<:encoding(utf8)> open layer), tell() will return byte offsets, not character offsets (because implementing that would render seek() and tell() rather slow). @@ -4974,10 +4974,10 @@ L<perlipc/"UDP: Message Passing"> for examples. Note the I<characters>: depending on the status of the socket, either (8-bit) bytes or characters are sent. By default all sockets operate on bytes, but for example if the socket has been changed using -binmode() to operate with the C<:utf8> I/O layer (see L</open>, or the -C<open> pragma, L<open>), the I/O will operate on UTF-8 encoded -Unicode characters, not bytes. Similarly for the C<:encoding> pragma: -in that case pretty much any characters can be sent. +binmode() to operate with the C<:encoding(utf8)> I/O layer (see +L</open>, or the C<open> pragma, L<open>), the I/O will operate on UTF-8 +encoded Unicode characters, not bytes. Similarly for the C<:encoding> +pragma: in that case pretty much any characters can be sent. =item setpgrp PID,PGRP X<setpgrp> X<group> @@ -6328,9 +6328,9 @@ POSITION, and C<2> to set it to EOF plus POSITION (typically negative). Note the I<in bytes>: even if the filehandle has been set to operate -on characters (for example by using the C<:utf8> I/O layer), tell() -will return byte offsets, not character offsets (because implementing -that would render sysseek() very slow). +on characters (for example by using the C<:encoding(utf8)> I/O layer), +tell() will return byte offsets, not character offsets (because +implementing that would render sysseek() very slow). sysseek() bypasses normal buffered IO, so mixing this with reads (other than C<sysread>, for example C<< <> >> or read()) C<print>, C<write>, @@ -6455,9 +6455,9 @@ the actual filehandle. If FILEHANDLE is omitted, assumes the file last read. Note the I<in bytes>: even if the filehandle has been set to -operate on characters (for example by using the C<:utf8> open -layer), tell() will return byte offsets, not character offsets -(because that would render seek() and tell() rather slow). +operate on characters (for example by using the C<:encoding(utf8)> open +layer), tell() will return byte offsets, not character offsets (because +that would render seek() and tell() rather slow). The return value of tell() for the standard streams like the STDIN depends on the operating system: it may return -1 or something else. diff --git a/pod/perlopentut.pod b/pod/perlopentut.pod index cd97fdce6a..18bc369bb4 100644 --- a/pod/perlopentut.pod +++ b/pod/perlopentut.pod @@ -917,7 +917,7 @@ second argument contains something else in addition to the usual C<< '<' >>, C<< '>' >>, C<< '>>' >>, C<< '|' >> and their variants, for example: - open(my $fh, "<:utf8", $fn); + open(my $fh, "<:crlf", $fn); =item * diff --git a/pod/perlrun.pod b/pod/perlrun.pod index 33d4f55db8..f345a78b7c 100644 --- a/pod/perlrun.pod +++ b/pod/perlrun.pod @@ -1124,9 +1124,9 @@ X<:utf8> A pseudolayer that turns on a flag on the layer below to tell perl that output should be in utf8 and that input should be regarded as -already in utf8 form. May be useful in PERLIO environment -variable to make UTF-8 the default. (To turn off that behaviour -use C<:bytes> layer.) +already in valid utf8 form. It does not check for validity and as such +should be handled with caution for input. Generally C<:encoding(utf8)> is +the best option when reading UTF-8 encoded data. =item :win32 X<:win32> diff --git a/pod/perlunicode.pod b/pod/perlunicode.pod index bd279f984c..61d62d219f 100644 --- a/pod/perlunicode.pod +++ b/pod/perlunicode.pod @@ -1523,7 +1523,7 @@ to work under 5.6, so you should be safe to try them out. A filehandle that should read or write UTF-8 if ($] > 5.007) { - binmode $fh, ":utf8"; + binmode $fh, ":encoding(utf8)"; } =item * diff --git a/pod/perlunifaq.pod b/pod/perlunifaq.pod index 4b2290abbf..b2913349cc 100644 --- a/pod/perlunifaq.pod +++ b/pod/perlunifaq.pod @@ -2,7 +2,7 @@ perlunifaq - Perl Unicode FAQ -=head1 DESCRIPTION +=head1 Q and A This is a list of questions and answers about Unicode in Perl, intended to be read after L<perlunitut>. @@ -16,6 +16,21 @@ is actually a generic C<Encode> tutorial and C<Encode> FAQ. But many people think that Unicode is special and magical, and I didn't want to disappoint them, so I decided to call the document a Unicode tutorial. +=head2 What character encodings does Perl support? + +To find out which character encodings your Perl supports, run: + + perl -MEncode -le "print for Encode->encodings(':all')" + +=head2 Which version of perl should I use? + +Well, if you can, upgrade to the most recent, but certainly C<5.8.1> or newer. +The tutorial and FAQ are based on the status quo as of C<5.8.8>. + +You should also check your modules, and upgrade them if necessary. For example, +HTML::Entities requires version >= 1.32 to function correctly, even though the +changelog is silent about this. + =head2 What about binary data, like images? Well, apart from a bare C<binmode $fh>, you shouldn't treat them specially. @@ -27,20 +42,9 @@ need text in a binary stream, encode your text strings first using the appropriate encoding, then join them with binary strings. See also: "What if I don't encode?". -=head2 What about the UTF8 flag? - -Please, unless you're hacking the internals, or debugging weirdness, don't -think about the UTF8 flag at all. That means that you very probably shouldn't -use C<is_utf8>, C<_utf8_on> or C<_utf8_off> at all. - -Perl's internal format happens to be UTF-8. Unfortunately, Perl can't keep a -secret, so everyone knows about this. That is the source of much confusion. -It's better to pretend that the internal format is some unknown encoding, -and that you always have to encode and decode explicitly. - =head2 When should I decode or encode? -Whenever you're communicating with anything that is external to your perl +Whenever you're communicating text with anything that is external to your perl process, like a database, a text file, a socket, or another program. Even if the thing you're communicating with is also written in Perl. @@ -88,23 +92,7 @@ Or if you already have an open filehandle: binmode $fh, ':encoding(UTF-8)'; Some database drivers for DBI can also automatically encode and decode, but -that is typically limited to the UTF-8 encoding, because they cheat. - -=head2 Cheat?! Tell me, how can I cheat? - -Well, because Perl's internal format is UTF-8, you can just skip the encoding -or decoding step, and manipulate the UTF8 flag directly. - -Instead of C<:encoding(UTF-8)>, you can simply use C<:utf8>. This is widely -accepted as good behavior when you're writing, but it can be dangerous when -reading, because it causes internal inconsistency when you have invalid byte -sequences. - -Instead of C<decode> and C<encode>, you could use C<_utf8_on> and C<_utf8_off>, -but this is considered bad style. Especially C<_utf8_on> can be dangerous, for -the same reason that C<:utf8> can. - -There are some shortcuts for oneliners; see C<-C> in L<perlrun>. +that is sometimes limited to the UTF-8 encoding. =head2 What if I don't know which encoding was used? @@ -146,6 +134,25 @@ UTF-8. If you properly encode your strings for output, none of this is of your concern, and you can just C<eval> dumped data as always. +=head2 Why do regex character classes sometimes match only in the ASCII range? + +=head2 Why do some characters not uppercase or lowercase correctly? + +It seemed like a good idea at the time, to keep the semantics the same for +standard strings, when Perl got Unicode support. While it might be repaired +in the future, we now have to deal with the fact that Perl treats equal +strings differently, depending on the internal state. + +Affected are C<uc>, C<lc>, C<ucfirst>, C<lcfirst>, C<\U>, C<\L>, C<\u>, C<\l>, +C<\d>, C<\s>, C<\w>, C<\D>, C<\S>, C<\W>, C</.../i>, C<(?i:...)>, +C</[[:posix:]]/>. + +To force Unicode semantics, you can upgrade the internal representation to +by doing C<utf8::upgrade($string)>. This does not change strings that were +already upgraded. + +For a more detailed discussion, see L<Unicode::Semantics> on CPAN. + =head2 How can I determine if a string is a text string or a binary string? You can't. Some use the UTF8 flag for this, but that's misuse, and makes well @@ -176,6 +183,45 @@ or by letting automatic decoding and encoding do all the work: open my $barfh, '>:encoding(BAR)', 'example.bar.txt'; print { $barfh } $_ while <$foofh>; +=head2 What are C<decode_utf8> and C<encode_utf8>? + +These are alternate syntaxes for C<decode('utf8', ...)> and C<encode('utf8', +...)>. + +=head2 What is a "wide character"? + +This is a term used both for characters with an ordinal value greater than 127, +characters with an ordinal value greater than 255, or any character occupying +than one byte, depending on the context. + +The Perl warning "Wide character in ..." is caused by a character with an +ordinal value greater than 255. With no specified encoding layer, Perl tries to +fit things in ISO-8859-1 for backward compatibility reasons. When it can't, it +emits this warning (if warnings are enabled), and outputs UTF-8 encoded data +instead. + +To avoid this warning and to avoid having different output encodings in a single +stream, always specify an encoding explicitly, for example with a PerlIO layer: + + binmode STDOUT, ":encoding(UTF-8)"; + +=head1 INTERNALS + +=head2 What is "the UTF8 flag"? + +Please, unless you're hacking the internals, or debugging weirdness, don't +think about the UTF8 flag at all. That means that you very probably shouldn't +use C<is_utf8>, C<_utf8_on> or C<_utf8_off> at all. + +The UTF8 flag, also called SvUTF8, is an internal flag that indicates that the +current internal representation is UTF-8. Without the flag, it is assumed to be +ISO-8859-1. Perl converts between these automatically. + +One of Perl's internal formats happens to be UTF-8. Unfortunately, Perl can't +keep a secret, so everyone knows about this. That is the source of much +confusion. It's better to pretend that the internal format is some unknown +encoding, and that you always have to encode and decode explicitly. + =head2 What about the C<use bytes> pragma? Don't use it. It makes no sense to deal with bytes in a text string, and it @@ -186,10 +232,36 @@ character counts for decoded data, and byte counts for encoded data. C<use bytes> is usually a failed attempt to do something useful. Just forget about it. -=head2 What are C<decode_utf8> and C<encode_utf8>? +=head2 What about the C<use encoding> pragma? -These are alternate syntaxes for C<decode('utf8', ...)> and C<encode('utf8', -...)>. +Don't use it. Unfortunately, it assumes that the programmer's environment and +that of the user will use the same encoding. It will use the same encoding for +the source code and for STDIN and STDOUT. When a program is copied to another +machine, the source code does not change, but the STDIO environment might. + +If you need non-ASCII characters in your source code, make it a UTF-8 encoded +file and C<use utf8>. + +If you need to set the encoding for STDIN, STDOUT, and STDERR, for example +based on the user's locale, C<use open>. + +=head2 What is the difference between C<:encoding> and C<:utf8>? + +Because UTF-8 is one of Perl's internal formats, you can often just skip the +encoding or decoding step, and manipulate the UTF8 flag directly. + +Instead of C<:encoding(UTF-8)>, you can simply use C<:utf8>, which skips the +encoding step if the data was already represented as UTF8 internally. This is +widely accepted as good behavior when you're writing, but it can be dangerous +when reading, because it causes internal inconsistency when you have invalid +byte sequences. Using C<:utf8> for input can sometimes result in security +breaches, so please use C<:encoding(UTF-8)> instead. + +Instead of C<decode> and C<encode>, you could use C<_utf8_on> and C<_utf8_off>, +but this is considered bad style. Especially C<_utf8_on> can be dangerous, for +the same reason that C<:utf8> can. + +There are some shortcuts for oneliners; see C<-C> in L<perlrun>. =head2 What's the difference between C<UTF-8> and C<utf8>? @@ -223,24 +295,9 @@ when you C<encode>. In other words: don't try to find out what the internal encoding for a certain string is, but instead just encode it into the encoding that you want. -=head2 What character encodings does Perl support? - -To find out which character encodings your Perl supports, run: - - perl -MEncode -le "print for Encode->encodings(':all')" - -=head2 Which version of perl should I use? - -Well, if you can, upgrade to the most recent, but certainly C<5.8.1> or newer. -The tutorial and FAQ are based on the status quo as of C<5.8.8>. - -You should also check your modules, and upgrade them if necessary. For example, -HTML::Entities requires version >= 1.32 to function correctly, even though the -changelog is silent about this. - =head1 AUTHOR -Juerd Waalboer <juerd@cpan.org> +Juerd Waalboer <#####@juerd.nl> =head1 SEE ALSO diff --git a/pod/perluniintro.pod b/pod/perluniintro.pod index ec5f6a47d8..ee61acfb02 100644 --- a/pod/perluniintro.pod +++ b/pod/perluniintro.pod @@ -167,7 +167,7 @@ as a warning: Wide character in print at ... -To output UTF-8, use the C<:utf8> output layer. Prepending +To output UTF-8, use the C<:encoding> or C<:utf8> output layer. Prepending binmode(STDOUT, ":utf8"); @@ -317,7 +317,9 @@ and on already open streams, use C<binmode()>: The matching of encoding names is loose: case does not matter, and many encodings have several aliases. Note that the C<:utf8> layer must always be specified exactly like that; it is I<not> subject to -the loose matching of encoding names. +the loose matching of encoding names. Also note that C<:utf8> is unsafe for +input, because it accepts the data without validating that it is indeed valid +UTF8. See L<PerlIO> for the C<:utf8> layer, L<PerlIO::encoding> and L<Encode::PerlIO> for the C<:encoding()> layer, and @@ -329,7 +331,7 @@ Unicode or legacy encodings does not magically turn the data into Unicode in Perl's eyes. To do that, specify the appropriate layer when opening files - open(my $fh,'<:utf8', 'anything'); + open(my $fh,'<:encoding(utf8)', 'anything'); my $line_of_unicode = <$fh>; open(my $fh,'<:encoding(Big5)', 'anything'); @@ -338,7 +340,7 @@ layer when opening files The I/O layers can also be specified more flexibly with the C<open> pragma. See L<open>, or look at the following example. - use open ':utf8'; # input and output default layer will be UTF-8 + use open ':encoding(utf8)'; # input/output default encoding will be UTF-8 open X, ">file"; print X chr(0x100), "\n"; close X; @@ -358,11 +360,6 @@ With the C<open> pragma you can use the C<:locale> layer printf "%#x\n", ord(<I>), "\n"; # this should print 0xc1 close I; -or you can also use the C<':encoding(...)'> layer - - open(my $epic,'<:encoding(iso-8859-7)','iliad.greek'); - my $line_of_unicode = <$epic>; - These methods install a transparent filter on the I/O stream that converts data from the specified encoding when it is read in from the stream. The result is always Unicode. @@ -411,13 +408,13 @@ by repeatedly encoding the data: local $/; ## read in the whole file of 8-bit characters $t = <F>; close F; - open F, ">:utf8", "file"; + open F, ">:encoding(utf8)", "file"; print F $t; ## convert to UTF-8 on output 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, or -explicitly opening also the F<file> for input as UTF-8. +UTF-8 encoded. A C<use open ':encoding(utf8)'> would have avoided the +bug, or explicitly opening also the F<file> for input as UTF-8. B<NOTE>: the C<:utf8> and C<:encoding> features work only if your Perl has been built with the new PerlIO feature (which is the default diff --git a/pod/perlunitut.pod b/pod/perlunitut.pod index 532804914f..6c7dfb057e 100644 --- a/pod/perlunitut.pod +++ b/pod/perlunitut.pod @@ -201,7 +201,7 @@ Gray. =head1 AUTHOR -Juerd Waalboer <juerd@cpan.org> +Juerd Waalboer <#####@juerd.nl> =head1 SEE ALSO |