Greets,
I have often seen people badmouth the bytes pragma, but there's one thing I use it for: cheaply identifying empty strings with bytes::length()when the strings may be carrying the SVf_UTF8 flag. The length() function can be inefficient for such strings, because it must traverse the entire buffer counting characters:
marvin@smokey:~/perltest $ perl compare_length_efficiency.pl
Rate utf8 bytes
utf8 4.35/s -- -98%
bytes 185/s 4154% --
marvin@smokey:~/perltest $
use strict;
use warnings;
use Benchmark qw( cmpthese );
# Make bytes:: functions available, but use character semantics.
use bytes;
no bytes;
cmpthese(
100,
{ bytes => sub {
my $smileys = "\x{263a}" x 10_000;
chop($smileys) while bytes::length($smileys);
},
utf8 => sub {
my $smileys = "\x{263a}" x 10_000;
chop($smileys) while length($smileys);
},
}
);
Is there an efficient alternative to bytes::length() for this use case elsewhere in core?
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