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# New Ticket Created by "Sisyphus"
# Please include the string: [perl #116569]
# in the subject line of all future correspondence about this issue.
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=116569 >
>From: sisyphus1@optusnet.com.au
>
>In a nutshell, with 5.17.7:
>
>$buffer = ‘some string’;
>$buf = $buffer;
>
>Then call an XSub that writes into $buf (by using sprintf, say).
>I then find that $buffer (which should not have changed) has also been
>written into, and is the same as $buf.
It's still the same behaviour in 5.17.8.
Is this how it's going to be in 5.18 ?
Again, here's a simple demo of how things have changed between 5.16 and
5.17.7/8:
####################################
use strict;
use warnings;
#use Inline C => Config =>
# BUILD_NOISY => 1;
use Inline C => <<'EOC';
SV * foo(char * buffer) {
char * c = "cow";
sprintf(buffer, "%s", c);
return newSVpv(buffer, 0);
}
EOC
my $buff = 'dog';
my $buf = $buff;
print "\$buf: $buf\n";
print "\$buff: $buff\n";
foo($buf);
print "\$buf: $buf\n";
print "\$buff: $buff\n";
####################################
On 5.17.7 and 5.17.8 that outputs
$buf: dog
$buff: dog
$buf: cow
$buff: cow
On 5.16 and earlier it outputs
$buf: dog
$buff: dog
$buf: cow
$buff: dog
For some (insane) reason an XS sub that changes the value of $buf, also
changes the value of $buff.
(Yet a perl sub that changes the value of $buf, does *not* change the value
of $buff.)
Cheers,
Rob
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