Re: global minor modes that can be overridden locally? [was: highlight-changes-mode]

[Lennart Borgman]

Richard Stallman wrote:
>     4. Perhaps an interface for #3 something like this?
>
>     - M-x foo-mode toggles the mode everywhere (including in buffers that have
>     local values?) - it is like using setq-default (should it also change the
>     local values?).
>
>     - C-u M-x foo-mode toggles the mode in the current buffer only - it is like
>     using setq with a local variable.
>
> That might be good.  However, I'd rather have the simplest call
> affect only the current buffer and use C-u to make it global.
>   
Why not define a new sub foo-mode-locally to toggle it in current buffer 
when it is a global minor mode? IMO that would be more easy to remember. 
Would it be harder to do it that way?