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:
>> As to the varhook feature itself: apart from the performance impact, it
>> also has the problem that one cannot usefully manipulate such a varhook
>> using add-hook or remove-hook.  That makes it a feature that does not
>> scale to multiple applications (like variable profiling).
>
> You can have multiple functions watch a symbol, and a function that
> watches multiple symbols. I don't understand the use case you're
> talking about that the varhook feature won't work for. Can you
> explain?

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.  So you manage to combine two
mechanisms intended for generality in a manner which no longer works in
general.

-- 
David Kastrup