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

[Kelly Dean]

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?

> Aaaand another data point.  You put in a fast access path for the case
> where the symbol has no properties.  However, if I do
[snip]
> So 76% of all variable accesses will be slowed down searching for the
> varhook property.  That seems expensive.

You're right. I've fixed it so property lists will no longer impact the speed, 
but I guess that doesn't matter if Stefan vetoes the feature.