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use strict;
use warnings;
## disable perl's warning mechanism
no warnings 'recursion';
use B 'svref_2object';
use Symbol 'qualify_to_ref';
sub change_depth_warn {
my($subname, $limit) = @_;
my $subref = \&$subname;
my $gv = svref_2object($subref)->GV;
my $lineno = 0;
no warnings 'redefine';
*{ qualify_to_ref $subname } = sub {
if( $gv->CV->DEPTH % $limit == 0 ) {
$lineno = do {
my $i = 0;
1 while caller $i++;
(caller($i - 2))[2]
} unless $lineno;
warn sprintf "Deep recursion on subroutine '%s' at %s line %d.\n", join('::', $gv->STASH->NAME, $gv->NAME), $0, $lineno;
}
&$subref(@_);
};
}
my $cnt = 0;
sub foo { &foo while $cnt++ < $_[0] }
my $maxdepth = 10;
my $recdepth = 30;
change_depth_warn('foo', $maxdepth);
printf "calling foo(), expecting %d warnings ...\n",
$recdepth / $maxdepth;
foo($recdepth);
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