use Devel::StackTrace;

sub calling_object {
  my $t = Devel::StackTrace->new;
  my $f;
  $f = $t->next_frame for (1..4);
  ($f->args)[0]
}

sub e {
  my $x = shift;
  print "x = $x\n";
  d('humma');
}

sub d {
  print "I was called by object ", calling_object(), "\n";
}

e('a', 'b', 'c');