Re: [OT] The joy of elisp

[Eric Schulte <eric.schulte@gmx.com>]

Marcelo de Moraes Serpa <celoserpa@gmail.com> writes:

> Here's a new version:
>
> (defun find-wiki-by-tags (tags)
>   (interactive "sEnter tags: ")
> (shell-command (format "cd ~/org;  ack \"\\* tags.*(%s).*\" --all" tags)
> "mybuf")
> (set-buffer "mybuf")
> (beginning-of-buffer)
> (ignore-errors
>   (while (search-forward-regexp "\\(.*?\\):")
>     (replace-match "[[~/org/\\1]]" )
>     ))
> (org-mode)
> )
>
> Problems:
>
> 1) It's slow, not sure where the bottleneck is (ack in itself is fast, I
> suppose the problem lies in elisp's side)

A pure elisp implementation would likely be faster, maybe something like
the following would work as an improvement

(defun org-files ()
  "Return a list of the files in the \"~/org/\" directory."
  (directory-files "~/org/" nil ".*.org$"))

(defun collect-links (tag)
  "Collect links in \"~/org/\" including TAG."
  (save-window-excursion           ; save the current buffer and point
    (let ((rx (format "^\\* tags.*%s" tag)) ; build a regexp for the given tag
          links)                            ; hold collected links
      (dolist (file (org-files)) ; for all files returned by `org-files'
        (find-file (expand-file-name file "~/org/"))  ; in this file
        (save-excursion
          (goto-char (point-min))       ; go to the beginning of the file
          (while (re-search-forward rx nil t) ; search for matches
            (push (org-store-link nil) links)))) ; save a link to the match
      links)))                          ; return the collected links

(defun find-wiki-by-tag (tag)
  "Pop to a buffer of links to headlines \"~/org/\" in including TAG."
  (pop-to-buffer (set-buffer (generate-new-buffer "*tag-matches*")))
  (org-mode)
  (dolist (link (collect-links tag))
    (insert link) (insert "\n")))

> 
> 2) The regexp is not optmized, and I'm getting some trash, although it
> lists the files for me so it works well enough now.
>

Try the `regexp-builder' function in one of your org files to
interactively build up a regexp and see what it matches.

In general the following two functions are very useful for finding
useful functions and documentation.

- describe-function :: used with tab completion to show documentation of
  functions

- elisp-index-search :: to look up documentation on broad elisp topics

Cheers,

>
> - Marcelo.
>
>
>
>
> On Mon, Dec 5, 2011 at 12:08 AM, Marcelo de Moraes Serpa <
> celoserpa@gmail.com> wrote:
>
>> Hi list!
>>
>> I decided to finally get my hands dirty and build a small function to
>> improve my org-based productivity system.
>>
>> Let me explain:
>>
>> I have a subdirectory under ~/org which has a bunch of files named after
>> different subjects. Originally it was supposed to model a wiki, but in
>> practice, I create a file there whenever I start studying a new (often
>> complex) subject and that I know I will come back often and edit / improve.
>> It's indeed like a wiki.
>>
>> However, I don't keep those files in the agenda. It would slow it down a
>> lot. To keep the organization as organic as possible, I simply use tags to
>> bring them together semantically. So, I have other files with items that
>> are tagged, say, business, and I have a "wiki file" with a headline like
>> this:
>>
>> * tags :business:
>>
>> <contents>
>>
>> I use the tags headline to tag those files.
>>
>> Now, what I wanted was to get a list of files related to say, the business
>> tag. It's quite useful to find myself in the (good) chaos of tagged "wiki
>> files", I came up with a small elisp function that does just that!
>>
>> (progn
>> (shell-command "cd ~/org;  ack \"\\* tags.*(business).*\" --all" "mybuf")
>> (set-buffer "mybuf")
>> (beginning-of-buffer)
>> (ignore-errors
>>   (while (search-forward-regexp "\\(.*?\\):")
>>     (replace-match "[[~/org/\\1]]" )
>>     ))
>> (org-mode)
>> )
>>
>> Bear in mind this is my first elisp program ever. It's not even a function
>> yet, actually. But it works pretty well for what I want :)
>>
>> Took me around 1 hour to bring it up.
>>
>> The joy of breaking your head on something!
>>
>> Cheers!
>>
>> (Suggestions on how to improve it welcome!)
>>
>> Marcelo.
>>

-- 
Eric Schulte
http://cs.unm.edu/~eschulte/