Re: [PATCH] Speed up project-kill-buffers

[Dmitry Gutov]

On 16.05.2021 23:36, Stephen Leake wrote:
> Which means you need to provide an option for the times when we want the
> other behavior: C-u kills root and external-roots, plain kills root only.

I wouldn't mind adding an option, but that presents a difficulty.

At the moment, we call `project-current` in each buffer and compare the 
returned value to the "current" project instance. That wouldn't work for 
external roots no matter what option we add because a given file inside 
"external root" can belong (in an "extended" sense) to several projects 
at once, so there's no logical way to obtain the project instance we're 
looking for based on such external file. Right?

A generic like project-contains? I previously mentioned would have a 
problem that every project backend's implementation would have to obey 
such an option, which creates new possibility for bugs and diverging 
behaviors.

If the current project-kill-buffers doesn't work for you (please check; 
IIRC your backend's peculiar behavior might have an upside in this 
case), what we could more easily do is create an option like 
'project-list-buffers-function'. The default would delegate to 
project-current. The alternative could indeed use file-in-directory-p 
(or a string comparison to similar effect) as discussed in this thread, 
providing a different inclusion semantics and improved performance, and 
the third alternative value could enable looking in external roots as well.