When should I concern myself with std::iostream::sentry?

Question

Online references have rather brief and vague descriptions on the purpose of std::iostream::sentry. When should I concern myself with this little critter? If it\'s

Answer 1

Most people will never write any code that needs to deal with creating sentry objects. A sentry object is needed when/if you extract data from (or insert it into) the stream buffer that underlies the stream object itself.

As long as your insertion/extraction operator uses other iostream members/operators to do its work, it does not have to deal with creating a sentry object (because those other iostream operators will create and destroy sentry objects as needed).