Nicolas,

Thanks for your feedback. I agree that using the same link type is better.

Hence I took an alternate approach as detailed in the attached patch.
Enhanced org-info-follow-link to attempt index lookup if node lookup fails.

Following is my check in message found in the attached patch:

    Enhanced org-info-follow-link to attempt index lookup if node lookup fails.

    Info index is almost always finer grain than info nodes. For example
    with this change, [[info:libc#close]] brings up not only
    "(libc)Opening and Closing Files" info node, but also place the cursor
    on the line that documents "close" function within the node. This is
    done by looking up "close"in the index upon failing to find a node
    named "close". Hence one can now link function, variable and other
    names that are in the index rather than being limited to info node
    names. Typically there are far more index items than there are node
    names. For example libc manual has about 700 nodes, but over
    4000 concept, type, function, and variables index items.

On 6 November 2014 10:41, Nicolas Goaziou <mail@nicolasgoaziou.fr> wrote:

Hello,

Richard Kim <emacs18@gmail.com> writes:

> A patch is provided below which implements a new link type called "infoi"
> as a complement to "info" type that exist already.

Thanks for your patch.

> Why new link type? Because info index is almost always finer grain
> than info nodes. For example [[infoi:libc#close]] brings up not only
> "(libc)Opening and Closing Files" info node, but also place the cursor
> on the line that documents "open" function within the node. Hence it
> is more useful to link function, variable and other names that are in
> the index. Most info documents have very rich indexes.

OK. I would have preferred to merge both features into the same link
type, but I see no elegant syntax to distinguish between a node and an
index search.

> I am not familiar with org coding style, so I share this patch to
> present the idea rather than as a finished patch that can be checked
> in. I assume that name changes and other changes will be needed prior
> to being acceptable for check in assuming that the idea is ok.

The idea is OK. Some comments follow.

> org-info.el: Add new link type "infoi" that looks up info file index.

No full stop at the end of the summary.

> * lisp/org-info.el (org-info-index-open): New function to implement
> new link type named "infoi".

"New function" is enough here.

You can describe the motivation behind the patch farther in the commit
message, after another blank line.

> +;;; info-index
> +
> +(org-add-link-type "infoi" 'org-info-index-open)
> +
> +(declare-function Info-index "info" (topic))
> +
> +(defun org-info-index-open (name)
> + "Follow an Info file and look up index item specified by NAME."
> + (if (or (string-match "\\(.*\\)[#:]:?\\(.*\\)" name)
> + (string-match "\\(.*\\)" name))
> + (let ((nodename (match-string 2 name)))
> + (require 'info)
> + (Info-find-node (match-string 1 name) "Top")
> + (if nodename ; If there isn't a node, choose "Top"
> + (Info-index nodename)))

Prefer `when' over one-armed `if'.

> + (message "Could not open: %s" name)))

This introduce some code duplication in "org-info.el". Could you factor
it out?

Regards,

--
Nicolas Goaziou