Re: Bug: org-babel-expand-noweb-references is very slow [9.1.9 (release_9.1.9-65-g5e4542 @ /usr/share/emacs/26.3/lisp/org/)]

[Diego Zamboni <diego@zzamboni.org>]

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Hi Vladimir,

The main difference I have noticed is that you can have multiple blocks
with the same :noweb-ref header argument, and they will be concatenated on
tangle. I use this in some of my files to progressively build a block of
code which is then referenced somewhere else. With #+name, you can have
only one block with each name, the others are discarded (can't remember if
it's the first or the last one that gets used).

I guess this is also why :noweb-ref tangling is slow, since all blocks need
to be scanned and put together.

--Diego


On Thu, Jan 9, 2020 at 2:43 AM Vladimir Nikishkin <lockywolf@gmail.com>
wrote:

> Ouch, that was unexpected.
>
> The manual for my version only includes four mentions if the noweb-ref
> header argument. Is it becoming deprecated?
>
> What does "apparently don't need" actually mean? That is, when should I
> use the name, and when the header argument? What can the header argument do
> that the name cannot?
>
>
> Nicolas Goaziou <mail@nicolasgoaziou.fr> 於 2020年1月9日 週四 01:23 寫道：
>
>> Hello,
>>
>> Vladimir Nikishkin <lockywolf@gmail.com> writes:
>>
>> > I am attaching the file in which tangling is still slow.
>> >
>> > The file is quite big, but that alone doesn't seem to be the reason
>> > for slowliness (I tried adding 1M-long words in the random places of
>> > the previous mwe).
>> >
>> > You can see the result by C-c C-v C-v'ing the code block at the
>> > "Ramanujan numbers" heading.
>> >
>> > Below is the profiler report for C-c C-v C-v'ing.with the heaviest
>> > blocks expanded:
>>
>> This is because you're using :noweb-ref, which _is_ slow, although you
>> apparently don't need it in the document. Use name keyword instead,
>> e.g.,
>>
>>     #+name: primetest
>>     #+begin_src scheme :exports both :results output
>>       (define (smallest-divisor n)
>>         (find-divisor n 2))
>>       (define (find-divisor n test-divisor)
>>         (cond ((> (square test-divisor) n) n)
>>           ((divides? test-divisor n) test-divisor)
>>           (else (find-divisor n (+ test-divisor 1)))))
>>       (define (divides? a b) (= (remainder b a) 0))
>>
>>       (define (prime? n)
>>         (= n (smallest-divisor n)))
>>     #+end_src
>>
>>
>> Regards,
>>
>> --
>> Nicolas Goaziou
>>
>

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