X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Fbytes.pm;h=3b0268e644747092e5bf8d0e287f7f396f202149;hb=843dbe2696b695867a2230e1af4a98d63d6c9559;hp=e8ab16f1bdb2afb2d63805263164a96977e4b1cc;hpb=657b208b434818aa5e54d68b0a8ad320c0252adf;p=p5sagit%2Fp5-mst-13.2.git diff --git a/lib/bytes.pm b/lib/bytes.pm index e8ab16f..3b0268e 100644 --- a/lib/bytes.pm +++ b/lib/bytes.pm @@ -1,11 +1,15 @@ package bytes; +our $VERSION = '1.00'; + +$bytes::hint_bits = 0x00000008; + sub import { - $^H |= 0x00000008; + $^H |= $bytes::hint_bits; } sub unimport { - $^H &= ~0x00000008; + $^H &= ~$bytes::hint_bits; } sub AUTOLOAD { @@ -30,17 +34,34 @@ bytes - Perl pragma to force byte semantics rather than character semantics =head1 DESCRIPTION WARNING: The implementation of Unicode support in Perl is incomplete. -Expect sudden and unannounced changes! +See L for the exact details. The C pragma disables character semantics for the rest of the lexical scope in which it appears. C can be used to reverse the effect of C within the current lexical scope. -Perl normally assumes character semantics in the presence of -character data (i.e. data that has come from a source that has -been marked as being of a particular character encoding). - -To understand the implications and differences between character +Perl normally assumes character semantics in the presence of character +data (i.e. data that has come from a source that has been marked as +being of a particular character encoding). When C is in +effect, the encoding is temporarily ignored, and each string is treated +as a series of bytes. + +As an example, when Perl sees C<$x = chr(400)>, it encodes the character +in UTF8 and stores it in $x. Then it is marked as character data, so, +for instance, C returns C<1>. However, in the scope of the +C pragma, $x is treated as a series of bytes - the bytes that make +up the UTF8 encoding - and C returns C<2>: + + $x = chr(400); + print "Length is ", length $x, "\n"; # "Length is 1" + printf "Contents are %vd\n", $x; # "Contents are 400" + { + use bytes; + print "Length is ", length $x, "\n"; # "Length is 2" + printf "Contents are %vd\n", $x; # "Contents are 198.144" + } + +For more on the implications and differences between character semantics and byte semantics, see L. =head1 SEE ALSO