Re: files.el: Once again impossible to turn off dir-settings

[Stefan Monnier]

> Stefan, --yes, /homee/user is nfs mounted -- and accessing
> non-existent directories in /home causes a network access.

So if I access /home/<foo>, which remote machine is being accessed?

> means that         when emacs  goes hunting in /home, it triggers
> a huge number of filer accesses.

In my experience, the actual number of accesses is not important.
What matters is whether one of them triggers access to a nonexistent
remote machine.  E.g trying to find /net/.dir-settings.el can cause the
autofs file system to try and contact the ".dir-settings.el" server
which doesn't exist (if you get lucky, you immediately get an error,
but you may also end up waiting for a timeout, and in any case you end
up waiting for DNS resolution, which can take a few seconds).

> I wasn't aware of the other regexp -- I'll use that.  But for the
> foreseeable future I expect to disable dir-setings -- at least until
> there is a project using it.

Sounds reasonable.

> I use Emacs for many things, including writing code, -- not
> exclusively for writing code; and for that use case, it's
> important that emacs not always go trawling around for project settings.

Dir settings are not only for "programming projects".  They can be used
for anything, just like file variables (which I actually tend to use
more in non-programming files).  Also as long as you don't have any
.dir-settings.el files, then the only difference between activating and
deactivating the feature is the time taken to to look up those files,
but since VC looks up several similar files anyway, the slow down should
be lost in the noise (unless you set vc-ignore-dir-regexp to a value
different from locate-dominating-stop-dir-regexp, as you've seen).


        Stefan