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86530b38 AT |
1 | package bytes; |
2 | ||
3 | our $VERSION = '1.00'; | |
4 | ||
5 | $bytes::hint_bits = 0x00000008; | |
6 | ||
7 | sub import { | |
8 | $^H |= $bytes::hint_bits; | |
9 | } | |
10 | ||
11 | sub unimport { | |
12 | $^H &= ~$bytes::hint_bits; | |
13 | } | |
14 | ||
15 | sub AUTOLOAD { | |
16 | require "bytes_heavy.pl"; | |
17 | goto &$AUTOLOAD; | |
18 | } | |
19 | ||
20 | sub length ($); | |
21 | ||
22 | 1; | |
23 | __END__ | |
24 | ||
25 | =head1 NAME | |
26 | ||
27 | bytes - Perl pragma to force byte semantics rather than character semantics | |
28 | ||
29 | =head1 SYNOPSIS | |
30 | ||
31 | use bytes; | |
32 | no bytes; | |
33 | ||
34 | =head1 DESCRIPTION | |
35 | ||
36 | The C<use bytes> pragma disables character semantics for the rest of the | |
37 | lexical scope in which it appears. C<no bytes> can be used to reverse | |
38 | the effect of C<use bytes> within the current lexical scope. | |
39 | ||
40 | Perl normally assumes character semantics in the presence of character | |
41 | data (i.e. data that has come from a source that has been marked as | |
42 | being of a particular character encoding). When C<use bytes> is in | |
43 | effect, the encoding is temporarily ignored, and each string is treated | |
44 | as a series of bytes. | |
45 | ||
46 | As an example, when Perl sees C<$x = chr(400)>, it encodes the character | |
47 | in UTF-8 and stores it in $x. Then it is marked as character data, so, | |
48 | for instance, C<length $x> returns C<1>. However, in the scope of the | |
49 | C<bytes> pragma, $x is treated as a series of bytes - the bytes that make | |
50 | up the UTF8 encoding - and C<length $x> returns C<2>: | |
51 | ||
52 | $x = chr(400); | |
53 | print "Length is ", length $x, "\n"; # "Length is 1" | |
54 | printf "Contents are %vd\n", $x; # "Contents are 400" | |
55 | { | |
56 | use bytes; | |
57 | print "Length is ", length $x, "\n"; # "Length is 2" | |
58 | printf "Contents are %vd\n", $x; # "Contents are 198.144" | |
59 | } | |
60 | ||
61 | For more on the implications and differences between character | |
62 | semantics and byte semantics, see L<perlunicode>. | |
63 | ||
64 | =head1 SEE ALSO | |
65 | ||
66 | L<perlunicode>, L<utf8> | |
67 | ||
68 | =cut |