Re: Shift selection using interactive spec

[Richard Stallman]

    As I understand the purpose of this feature is practically to move
    the last expression of the command's body that usually is written as

        (if (interactive-p)
            (message "Result of this command is %.0f" return-value)
          (format "%.0f" return-value))

You have the right idea in mind for what the code would be trying to
do.  But code like that would be a strange way to write it, and in
practice does seem to occur much if at all.  The way I would envision
this is more like

        (if interactive-call
            (message "Result of this command is %.0f" return-value))
        return-value)

where `interactive-call' is an argument initialized to non-nil
for an interactive call.

The job of the second arg to `interctive', that I've proposed, would
be to control how to generate the message in the interactive case.