Glenn Morris <rgm@gnu....> writes:

> I discussed this with Stefan off-list some time ago.
> Still waiting for "dlet"... :)
>
>> > Eg diary-list-entries has always advertized NUMBER and
>> > ORIGINAL-DATE as available for use in the hook functions it
>> > calls. It's widely used within the calendar, and probably outside
>> > as well. It's not how I would have implemented it, but here we are.
>>
>> > The only way I can think to change it is to make it respect both eg
>> > DIARY-NUMBER and NUMBER equally, with a view to removing NUMBER in
>> > future.

I think we should bite the bullet and introduce new defvars with
properly prefixed names, as was done for `e'.  We can have a transition
period during which the diary binds both the new variables and the old
ones, then eliminate the old ones in (say) Emacs 25.  Any third party
code that wants backward compatibility with old Emacs versions can check
if the new variables are bound, and use them first.