Ok, here it is the full solution using an in-memory file:
use strict;
use warnings;
use Path::Tiny;
sub hotpatch {
my ($self, $module) = @_;
if ($module eq 'AnyEvent/DNS.pm') {
for my $inc (@INC) {
next if ref $inc;
if (open my $in, '<', path($inc)->child($module)) {
my $buffer = do { undef $/; <$in> };
$buffer =~ s/\bsub\s+DOMAIN_PORT\b/sub DOMAIN_PORT ()
+{ 1053 } sub FORMER_DOMAIN_PORT/;
open my $out, '<', \$buffer
or die "Couldn't patch AnyEvent::DNS; your Perl do
+es not support in-memory filehandles";
return $out;
}
}
warn "couldn't patch AnyEvent::DNS";
}
return undef;
}
BEGIN { unshift @INC, \&hotpatch }
use AnyEvent::DNS;
BEGIN { @INC = grep not(ref and $_ eq \&hotpatch), @INC }
say AnyEvent::DNS::DOMAIN_PORT();
say AnyEvent::DNS::FORMER_DOMAIN_PORT();