Re: Last use of defadvice in Emacs

["T.V Raman" <raman@google.com>]

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Stefan Monnier <monnier@iro.umontreal.ca> writes:
Relevant pieces retained alongside responses:

>> 2. Re ad-return-value -- I've almost never had to explicitly set
>>    ad-return-value -- in around and after advice, I have always
>>    returned ad-return-value and have never hit issues --- perhaps
>>    because I've always wrappered my advice body in a let form --
This has never bitten emacspeak because I always leave the return value
>>    unmolested, and for safely always make sure that ad-return-value
>>    is the last form in the advice body so that functions or code that
>>    runs after the advice doesn't break because the original
>>    function's return value got dropped along the way 


>>    not sure. What kind of breakages happen when returning
>>    ad-return-value vs explicitly setting ad-return-value at the end
>>    of the advice body?
>
> You typically need to set it when you want to do:
>
>     (defadvice some-function (around my-advice activate)
>       (if (bla bla)
>           (cons 1 ad-do-it)
>         (do something else)
>         (and return some value)))
>
> which needs to be something like:
>
>     (defadvice some-function (around my-advice activate)
>       (if (bla bla)
>           (progn ad-do-it
>             (push 1 ad-return-value))
>         (do something else)
>         (setq ad-return-value (and return some value))))
>
>>       3. I've avoided the complexity around preactivation vs
>>          activation etc by always saying (... pre act comp) in all my

Avoid complexity here == "my little brain doesn't have to worry about
it" --- all the calls to defadvice in emacspeak say "pre act comp"
which means if it needs changing, I can change them all with a single
line of perl or sed magic.

>>          advice forms
>
> Not sure in which sense this "avoided the complexity".
> And most people reading your code won't know what it means, I'm afraid.
>
>
>         Stefan
>
>

-- 

Thanks,

--Raman(I Search, I Find, I Misplace, I Research)
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