[draegtun]

Another solution could be to lock the keys of $config after its been configured:

  use Hash::Util 'lock_keys';

  our $config;
  $config->{file_paht} = "/opt/app/data_file";
  lock_keys( %$config );

Now any attempt to use an undefined key will throw an error. So on the open() it would now throw error: Attempt to access disallowed key 'file_path' in a restricted hash at...

[douglashunter]

This is what Kris Arnold (https://twitter.com/wka), one of the other hackers here at Shutterstock recommended. I like it.

[draegtun]

Me to, especially as it covers both problems you've given in the post.

Now I just need to get into the habit of using Hash::Util::lock_keys more often myself :)