Functors and commands: accessing and changing document data

Functors are used by the Basic Document framework to implement document surrogates. If you want to operate on a remote document, use a surrogate (obtained from a document reference). Use functors to access data, commands to change data. (This distinction is enforced by the design of the Compound Document framework.)

Commands are part of a more sophisticated system that permits selection of subsets of data. This system is fully developed in the Compound Document framework.