Re: Shift selection using interactive spec

[Richard Stallman]

    OTOH, shift-selection doesn't tell how to read arguments, It even doesn't
    define the meaning of a command.  It specifies the behavior of a separate
    optional feature invoked before the command call (in this case to set the
    mark before the command call).

The general purpose of `interactive' is to specify how to call the
command interactively.  This fits perfectly into that perfect.

I've long thought about giving `interactive' a second argument that
would specify how to display the command's return value.  This would
make it convenient to write commands that would return certain
information as a value when called from Lisp, and display the
same information when called interactively.