Subject: Re: bug#20090: 24.4: linking to a position within an info node

From: Boruch Baum <[email-masked]>
Date: Fri, 13 Mar 2015 10:58:58 -0400

On 03/12/2015 03:50 PM, Juri Linkov wrote:
>> When the org mode manual discusses creating links, it gives an example
>> of linking to an info node (the self-referencing example is
>> `info:org#External' links). The manual continues, at node
>> `info:org#Search options', to describe how specific positions within
>> file links can be directly specified. This does work for links to
>> regular files, but does not work for positions within an info node (eg.
>> line 85 of node x).
> 
> Is there an official format for the line numbers in Info cross-references?
I don't know - my assumption was that within emacs, it would be
basically just another type of emacs buffer, and be a legitimate subject
for all elisp commands.

Your question got me thinking, that emacs may have subtle rendering
quirks, so just now, I opened fresh instances of info buffers in both
very wide and very narrow windows, and they both `fill' to the same line
length, ie the wide window has a lot of right-side white-space, and the
narrow window has lines wrapped.

Since I submitted the bug report, I've continued trying to get the
feature working, and have been experimenting with the org-mode hooks
`org-create-file-search-functions' and
`org-execute-file-search-functions' to no success. The only, supposedly
working examples I've come across for these functions are [1] and [2].
If you know of other resources, that could be helpful.

One other possible related bug I've found is that when trying to use
org-store-link for a particular line number within an org-file, the link
is created to the most recent header. One can successfully, manually,
hack the created link, replacing the reference to the header with a line
number, in order to be able to navigate directly to the desired line
(all this, for a link target in an org mode file - this was done as a
test, once I came across the original bug) [3].

[1]
https://stackoverflow.com/questions/10681766/emacs-org-mode-textual-reference-to-a-fileline

[2] http://www.emacswiki.org/emacs/.emacs-DominiqueQuatravaux.el

[3] info:org#Search options

> 
> (info "(texinfo) Printing Indices & Menus") documents the format of
> line numbers only in the index, not in the cross-references:
> 
>    * In Info output, `@printindex' produces a special menu containing
>      the line number of the entry, relative to the start of the node.
>      Info readers can use this to go to the exact line of an entry, not
>      just the containing node.  (Older Info readers will just go to the
>      node.)  Here's an example:
> 
>           * First index entry:   Top.   (line  7)
> 
>      The actual number of spaces is variable, to right-justify the line
>      number; it's been reduced here to make the line fit in the printed
>      manual.
> 
> The Info reader already supports this format in the index.
> 

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