Re: Shift selection using interactive spec

[Richard Stallman]

    And then another simplest alternative we could provide is t when the
    return value should be displayed with just `(message "%s" ret-val)':

There's no harm in that, but usually the command should add some text
around the return value.  So I think use of t would be rather rare.
Using a format string would be the more common case.

What I am not sure of is whether the existing format string feature
is powerful enough for most of the real cases.