sub try_hard {
  my $sub = shift;
  my $tries = 3;
  my @failures;
  while($tries--) {
    eval {
      my $success = $sub->(@_) or die "sub returned false value";
      1;
    } or do {
      push @failures,$@;
    }
  }
  die "try_hard: Failed 3 times: $failures[-1]"
}

这可能会失败：

try_hard: Failed 3 times: sub returned false value at BadUtils.pm line 7

…如果您在许多地方调用try_hard并且您不知道哪个呼叫是软故障的呼叫,则无效.

如果我能得到$sub的来源,我可以将其变为：

my $success = $sub->(@_) or die "sub returned false value at $file line $lineno
";

并且库将略微DWIMmer.是否有可能实现这一目标？