Re: Adding support for limits and exclusions to iCal recurring events

[Nicolas Goaziou <n.goaziou@gmail.com>]

Hello,

Toke Høiland-Jørgensen <toke@toke.dk> writes:

> Handling it in the agenda can be done by an exclusion function. I
> currently have this in my org-agenda-skip-function-global (along with
> another function to skip items after their END_DATE):
>
> (defun thj/skip-excluded ()
>   "Skip agenda items on dates in EXCLUDE property"
>   (when (and (boundp 'date) date)
>     (let ((excluded-string (thj/get-property "EXCLUDE"))
>           exclusions)
>       (when excluded-string
>         (setq exclusions (mapcar
>                           (lambda (ex-date-string)
>                             (equal date (org-date-to-gregorian
>                                           (org-parse-time-string ex-date-string))))
>                           (split-string excluded-string ",")))
>         (when (memq t exclusions)
>           (org-end-of-subtree t))))))
>
> (Should probably be updated to use the org native property extraction
> mechanism, but this predates my discovery of that).

This is a separate issue anyway: it belongs to a new thread. IMO, it's
an interesting feature to be able to stop a repeated event.

>> On the other hand, I'm not sure about the END_DATE property. Couldn't
>> DEADLINE be used for that matter? For example, `repeater-end-date'
>> could be added to `org-icalendar-use-deadline' possible values. When
>> this symbol belongs to variable's value and current entry has a
>> deadline, any timestamps with a repeater get deadline's value as its
>> END DATE property.
>>
>> What do you think?
>
> Sure, that would work. Two possible issues spring to mind:
>
> 1. Is there any use cases where someone might want a deadline (in its
> current use) along with an end date? Or some other conflict?

I would be great to have feedback from other iCalendar users about it.

> 2. Will using the DEADLINE field make it harder to add exclusion from
> the agenda? (I've never really used the deadline field, so don't know
> what people normally use it for).

I'm clearly no Agenda specialist. I thought a DEADLINE would end
a repeated event already. If it's not the case, does it make sense to
implement it too?

>>> +(defun org-icalendar-zero-convert-timestamp (timestamp &optional format)
>>> +  "Parse and format an org-formatted timestamp, zeroing the time component."
>>> +  (let ((time (org-parse-time-string timestamp))
>>> +	(fmt (or format "%Y%m%dT%H%M%SZ")))
>>> +    (format-time-string fmt (encode-time 0 0 0 (nth 3 time) (nth 4 time) (nth 5 time)))))
>>
>> Can't `org-icalendar-convert-timestamp' be used instead?
>
> It could, conceivably. However, I couldn't find any functions that would
> parse a property string into the timestamp format expected by
> org-icalendar-convert-timestamp,

I agree it's not obvious, but:

  (car (org-element-parse-secondary-string "<2013-07-24 Wed>" '(timestamp)))

should do the job.

You can set minutes and hours to 0 in the returned object, but it's not
easier than creating a new function indeed.


Regards,

-- 
Nicolas Goaziou