Re: virtual file buffer spanning multiple physical files

[Ted Zlatanov <tzz@lifelogs.com>]

On Sat, 02 Oct 2010 21:56:39 +0100 Juri Linkov <juri@jurta.org> wrote: 

JL> FUSE (Filesystem in Userspace) is useful for writing virtual filesystems,
JL> but it's not a system for virtual files :)  You can use FUSE to write
JL> a filesystem that allows to edit multiple physical files through
JL> one virtual file.

Yes.

>> I was thinking that would actually (with some folding
>> magic) be extremely useful in Emacs.  There are many cases where I edit
>> multiple small files and have to switch back and forth to see their
>> contents.  Also, search-and-replace would be easier.
>> 
>> Is there any existing mode that does that kind of virtual join?

JL> We considered such a mode some time ago in
JL> http://thread.gmane.org/gmane.emacs.devel/120943

JL> Maybe this multi-file mode (a buffer with multiple files) could be
JL> implemented like a multi-mode mode (a buffer with multiple major modes).

Maybe.  I was also thinking about the (not too old) discussion about
virtual file buffers that edit just a portion of a large file because
the max buffer size is smaller than the file and, of course, loading a
large file to overwrite a few bytes is very expensive.  Also the
multi-mode concept as seen in MuMaMo is quite useful.  So I think it's
good to start thinking about "stitched" buffers, consisting of multiple
"windows" into multiple files, each window of variable size and with its
own mode.  That would be ridiculously powerful and probably a pretty
big effort.  As a hack it could probably be done with text properties
but I don't know enough about the buffer structures in Emacs to say.

Ted