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- package bytes;
- our $VERSION = '1.04';
- $bytes::hint_bits = 0x00000008;
- sub import {
- $^H |= $bytes::hint_bits;
- }
- sub unimport {
- $^H &= ~$bytes::hint_bits;
- }
- sub AUTOLOAD {
- require "bytes_heavy.pl";
- goto &$AUTOLOAD if defined &$AUTOLOAD;
- require Carp;
- Carp::croak("Undefined subroutine $AUTOLOAD called");
- }
- sub length (_);
- sub chr (_);
- sub ord (_);
- sub substr ($$;$$);
- sub index ($$;$);
- sub rindex ($$;$);
- 1;
- __END__
- =head1 NAME
- bytes - Perl pragma to force byte semantics rather than character semantics
- =head1 NOTICE
- This pragma reflects early attempts to incorporate Unicode into perl and
- has since been superseded. It breaks encapsulation (i.e. it exposes the
- innards of how the perl executable currently happens to store a string),
- and use of this module for anything other than debugging purposes is
- strongly discouraged. If you feel that the functions here within might be
- useful for your application, this possibly indicates a mismatch between
- your mental model of Perl Unicode and the current reality. In that case,
- you may wish to read some of the perl Unicode documentation:
- L<perluniintro>, L<perlunitut>, L<perlunifaq> and L<perlunicode>.
- =head1 SYNOPSIS
- use bytes;
- ... chr(...); # or bytes::chr
- ... index(...); # or bytes::index
- ... length(...); # or bytes::length
- ... ord(...); # or bytes::ord
- ... rindex(...); # or bytes::rindex
- ... substr(...); # or bytes::substr
- no bytes;
- =head1 DESCRIPTION
- The C<use bytes> pragma disables character semantics for the rest of the
- lexical scope in which it appears. C<no bytes> can be used to reverse
- the effect of C<use bytes> within the current lexical scope.
- Perl normally assumes character semantics in the presence of character
- data (i.e. data that has come from a source that has been marked as
- being of a particular character encoding). When C<use bytes> is in
- effect, the encoding is temporarily ignored, and each string is treated
- as a series of bytes.
- As an example, when Perl sees C<$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<length $x> returns C<1>. However, in the scope of the
- C<bytes> pragma, $x is treated as a series of bytes - the bytes that make
- up the UTF8 encoding - and C<length $x> 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.
- For more on the implications and differences between character
- semantics and byte semantics, see L<perluniintro> and L<perlunicode>.
- =head1 LIMITATIONS
- bytes::substr() does not work as an lvalue().
- =head1 SEE ALSO
- L<perluniintro>, L<perlunicode>, L<utf8>
- =cut
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