Re: [PATCH] Proposal to change cursor appearance to indicate region activation

[David Kastrup <dak@gnu.org>]

Kelly Dean <kelly@prtime.org> writes:

> David Kastrup wrote:
>> Multiple independent use cases.  add-hook/remove-hook is a mechanism for
>> organizing independent use cases for one feature, but there is no such
>> mechanism for organizing independent use cases for the varhook feature
>> in your implementation even though you actually use add-hook.  But it
>> requires first individually allocating, naming, and using a hook for any
>> variable you might want to varhook into.
>
> IIUC, you mean independent uses of varhook might choose different
> symbols for the hook. It seems that would be solved by the convention
> of using the symbol ⌜foo-varhook⌝ as the hook for ⌜foo⌝; all
> independent uses would add/remove their functions on that same hook.

A convention is not an interface.

> I guess another solution would be to put the car of the list of
> functions directly in a dedicated varhook slot for the target symbol,
> rather than indirecting through a regular hook. That would increase
> the size of each symbol from 24 to 28 bytes (on 32-bit platforms). But
> even in my main Emacs session, which has been up for 54 days (with
> 300MB reserved memory), I only have 10k symbols, so an extra 40kB of
> memory usage isn't much overhead.

I have 40k right now, and this session has been up for few minutes
(admittedly, using desktop-load).  But at any rate, this does not appear
like a feature that should be a central part of the data/operation in a
production Emacs, and consequently it should not be a required part of
the implementation of a production Emacs feature either.

I also have to warn you that there is little point in trying to convince
or coax me since I more or less have the authority of a court jester.
So it is pointless to argue away problems with me since it does not help
getting the code accepted.

-- 
David Kastrup