X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Fbytes.pm;h=b7fabbf359d1a85bc34e7934a2abaf1bcd89c27b;hb=3a0105ce22d984a07f87a03826385acd066a988a;hp=0424e1778da9bd374f8bfa9602238e00957742a6;hpb=8058d7abf600e878367b422ec507695e4ac6f25a;p=p5sagit%2Fp5-mst-13.2.git diff --git a/lib/bytes.pm b/lib/bytes.pm index 0424e17..b7fabbf 100644 --- a/lib/bytes.pm +++ b/lib/bytes.pm @@ -1,50 +1,88 @@ -package byte; +package bytes; + +our $VERSION = '1.03'; + +$bytes::hint_bits = 0x00000008; sub import { - $^H |= 0x00000008; + $^H |= $bytes::hint_bits; } sub unimport { - $^H &= ~0x00000008; + $^H &= ~$bytes::hint_bits; } sub AUTOLOAD { - require "byte_heavy.pl"; - goto &$AUTOLOAD; + require "bytes_heavy.pl"; + goto &$AUTOLOAD if defined &$AUTOLOAD; + require Carp; + Carp::croak("Undefined subroutine $AUTOLOAD called"); } -sub length ($); +sub length (_); +sub chr (_); +sub ord (_); +sub substr ($$;$$); +sub index ($$;$); +sub rindex ($$;$); 1; __END__ =head1 NAME -byte - Perl pragma to force byte semantics rather than character semantics +bytes - Perl pragma to force byte semantics rather than character semantics =head1 SYNOPSIS - use byte; - no byte; + use bytes; + ... chr(...); # or bytes::chr + ... index(...); # or bytes::index + ... length(...); # or bytes::length + ... ord(...); # or bytes::ord + ... rindex(...); # or bytes::rindex + ... substr(...); # or bytes::substr + no bytes; + =head1 DESCRIPTION -WARNING: The implementation of Unicode support in Perl is incomplete. -Expect sudden and unannounced changes! +The C pragma disables character semantics for the rest of the +lexical scope in which it appears. C can be used to reverse +the effect of C within the current lexical scope. + +Perl normally assumes character semantics in the presence of character +data (i.e. data that has come from a source that has been marked as +being of a particular character encoding). When C is in +effect, the encoding is temporarily ignored, and each string is treated +as a series of bytes. + +As an example, when Perl sees C<$x = chr(400)>, it encodes the character +in UTF-8 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; # or "require bytes; bytes::length()" + print "Length is ", length $x, "\n"; # "Length is 2" + printf "Contents are %vd\n", $x; # "Contents are 198.144" + } + +chr(), ord(), substr(), index() and rindex() behave similarly. -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. +For more on the implications and differences between character +semantics and byte semantics, see L and L. -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). +=head1 LIMITATIONS -To understand the implications and differences between character -semantics and byte semantics, see L. +bytes::substr() does not work as an lvalue(). =head1 SEE ALSO -L, L +L, L, L =cut