RE: isearch multiple buffers

["Drew Adams" <drew.adams@oracle.com>]

> >> Perhaps the best way to specify a set of buffers to search as a unit
> >> is with a fileset.
> >
> > For those of us unfamiliar with that, could someone please
> > summarize what that is and how it would work in this context?
>
> See (info "(emacs)Filesets").

I see. Thanks.

> We definitely could implement isearch through filesets too, but it seems
> defining a fileset just to search though some buffers is not the simplest
> way to do this.
>
> Since you suggested to start isearch from the *Buffer List*, you could
> compare this method with starting isearch on filesets.

From a cursory look, I'd say that Buffer List should be used. This is about
searching buffers, not necessarily file buffers.

However, there is a fileset command (`filesets-open') to visit all of the
files in a fileset. And if (some or) all are open, then another (new)
fileset command, say `filesets-mark-buffers', could mark the corresponding
buffers. That way, the interface to isearch would still be Buffer List, but
there would be an easy way to search all files in a fileset.

Users should not be obliged to define a fileset in order to search multiple
buffers, but if they happen to have a fileset defined, then the same
mechanism can be used to let them mark and search the buffers of its files.

How should command `filesets-mark-buffers' react if only some of a fileset's
files are open (visited)? A strict behavior would have it do nothing,
requiring you to first open them all. A lax behavior would simply mark all
existing buffers that correspond to files in the fileset, whether or not
they are all open.

I don't know if the lax behavior would be useful or confusing (or both). My
guess is that it could be useful: You can open all files in a fileset if you
want to, or you can (manually) open only some of them. Even in the latter
case, you could then mark all of those that are open, in one fell swoop. One
possibility is to let the user choose strict or lax behavior, via an option.

BTW, even in the case of searching multiple file buffers, the doc language
should speak of it that way, and not in terms of searching "files".
Searching a set of files does not imply visiting them. The language of
isearch should speak of searching buffers, not files, whether or not
filesets are involved.