Re: breadcrumbs for Info . . . . . .

[Juri Linkov <juri@jurta.org>]

>> When nodes are in different files, visiting all ancestor nodes means
>> visiting several files that is slow on slow machines/connections.
>> For instance, the first node in the file info/emacs-4 is:
>>
>>   File: emacs,  Node: Fortran Indent,  Next: Fortran
>> Comments,  Prev: Fortran Motion,  Up: Fortran
>>
>>   31.13.2 Fortran Indentation
>>
>> So to display this node, it needs to open the file info/emacs-3 that
>> contains its parent node Fortran, and the top file info/emacs-1.
>
> Yes, I know that. But can you point to a particular node in a particular manual
> that you find is too slow?
>
> I checked (using `T') all of the manuals that come by default with Emacs on
> Windows - I found no nodes deeper than 4. I didn't check each level 4 node in
> each manual, but I checked several, and I see no performance problem. Perhaps
> you can find a level 4 node whose levels 1-3 are in different subfiles, and you
> can check whether it is too slow?
>
> IOW, is this a real problem in practice or just a hypothetical problem?

There were reports about Info taking substantial time to read
Info subfiles on slow connections.  You can search for e.g.
"Info slow connection" keywords and find posts like
http://thread.gmane.org/gmane.emacs.devel/17436/focus=18058
I don't know how often such situations happen nowadays.

Anyway, Info already scans the whole manual on the first visit
to find the index nodes, so it could build an internal node tree
as well on the same pass.

There is also another visual problem: when Info-hide-note-references
is nil, the displayed breadcrumbs line is not nice looking:

*Note Top:: > *Note Files::  > *Note Saving::  > *Note Backup::

-- 
Juri Linkov
http://www.jurta.org/emacs/