This defines the policy for file I/O with modules such as
File::Slurp::WithinPolicy. The purpose is to allow systems administrators to
define locations and restrictions for applications' file I/O and give app
developers a policy to follow. Note that the module doesn't ENFORCE the
policy - application developers can choose to ignore it
(and systems administrators can choose not to install their applications
 if they do!).

You may control which policy gets applied by creating a File::Policy::Config
module with an IMPLEMENTATION constant. You may write your own policy as a
module within the File::Policy:: namespace.

By default (if no File::Policy::Config is present), the File::Policy::Default
policy gets applied which doesn't impose any restrictions and provides
reasonable default locations for temporary and log files.