Re: Patch to improve org date manipulation

["Bart Bunting" <bart@xxxxxxxxxxx>]

Hi Raman,

Thanks for taking the time to provide a clear explanation.

I think there is a slight misunderstanding as to the behaviour I was
trying to get.  Although your implementation covers a case I was not
considering which is that it only speaks the timestamp, where my one
would read text after the timestamp as well.

The real difference is that if for example I change the day using my
version All I hear read is the day number and weekday name.  If I change
the month then I hear the month, day and weekday name and so on for the
year.

The advantage of this is when you are changing the day or time up and
down you hear only the relevant information which is the day or time
that changed and not the bits such as year and month that did not.

A side effect of checking for differences between the two strings is
that if you are moving by day and happen to cross a month boundary then
the month is spoken as well as the day.

So to get this behaviour back but leveraging what you have found about
the date being stored by org can I do something like this:

- revert to around advice
- capture the org-last-changed-timestamp before calling ad-do-it
- compare the two values and speak the difference.

Given your advice regarding the use of append can you suggest an idiom
to achieve the same thing where you have two strings and you want to
find the first difference?


   

>
> Couple of comments on  your original patch.
>
> 1. Note that emacs provides built-in functions
> line-beginning-position and line-end-position -- so you dont need
> to do a save-excursion and move point to beginning of line, etc.
>
>
> 2. The idiom of turning a string into a list of chars, popping
> off the front etc is very Pythonic and would perform well in
> Python; it is not a good idiom to use in Lisp code, it would
> perform badly.
>
>  Moreover , it  wouldn't readily make sense to someone reading lisp code
> (I had to read it twice to understand it):-)  This is more a
> question of idioms and culture variations in different languages,
> but is good to be aware of since it's the common idioms that are
> also good with respect to performance. In lisp, if you turn a
> string into a list of chars, you end up   creating new memory.
>
> 3. In this case, I went back and looked at the implementation in
> org-mode for the functions being advised.
>
> Reasoning: if that function  was
> going to display that timestamp, and that was what we wanted to
> speak, then it would be easier to find that string, rather than
> doing a diff of the previous contents with the new contents.
>
> This then took me to the function that computes the timestamp
> string to display. I alsos noticed that not only does the
> function computing the string to display return that string as
> its return value, org actually caches it in a variable. If org
> hadn't cached it, then I would have advised that function to
> cache the variable in an emacspeak created variable -- a useful
> trick to keep in mind.
>
> 4. But since org caches it in a named variable, I went ahead and
> used it in the advice.
>
> 5. I also turned it into an after advice since it doesn't look
> like we need the power of an around advice. So the explanation
> turned out to be longer than the code;-)
>
> `(defadvice ,f (after emacspeak pre act comp)
>           "Provide auditory feedback."
>           (when (ems-interactive-p )
>             (emacspeak-auditory-icon 'select-object)
>             (dtk-speak org-last-changed-timestamp)))
> -- 
>
> -- 
>
> -- 
>
> -- 
>
>
> On 5/9/13, Bart Bunting <bart@xxxxxxxxxxx> wrote:
>> Good afternoon,
>>
>> Please find attached a small patch that modifies the way emacspeak
>> speaks org dates when they are changed with s-up and s-down.
>>
>> Previously emacspeak would speak the entire line.  I found this a little
>> verbose and wanted to hear just the relevant information.
>>
>> This patch attempts to address this by doing the following:
>> - Compare the date before and after the change.
>> - Find where the two strings differ.
>> - Move point to the difference and then move back past any numbers.
>> - Speak the line from this point.
>>
>>
>> I welcome peoples thoughts on both the efficacy of this aproach and my
>> coding style.
>> .
>> Kind regards
>>
>> Bart
>>
Bart
-- 


Kind regards

Bart

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