use strict;
use warnings;


our $var  = 10;
our $keep = 20;


print "\$var  = $var\n";
print "\$keep = $keep\n";

print "Reset <<\$$_>>\n" for dangerous_reset(qr/^v/);

print "\$var  = $var\n";
print "\$keep = $keep\n";


sub dangerous_reset {
  my $criteria = shift;
  my $package = (caller)[0] . '::';
  {
    no strict 'refs';
    my @wanted = grep {    /$criteria/                      # Meets criteria
                        && defined *{$package . $_}{SCALAR} # Has scalar element
                        && /^[\p{alpha}_]\w*$/              # Isn't special.
                 } keys %{$package};
    undef ${*{$package . $_}{SCALAR}} for @wanted;
    return @wanted; # Return count, or list of variables removed.
  }
}