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From: John Kitchin <jkitchin@andrew.cmu.edu>
To: Greg Minshall <minshall@umich.edu>
Cc: tomas@tuxteam.de, emacs-orgmode@gnu.org
Subject: Re: Get =#+RESULTS= without re-evaluating source code block?
Date: Mon, 01 Feb 2021 21:10:39 -0500	[thread overview]
Message-ID: <m28s87i5i8.fsf@andrew.cmu.edu> (raw)
In-Reply-To: <1342984.1611804377@apollo2.minshall.org>

I discovered that it matters a lot which block you cache. You have to
cache the long running block. I had put cache on the block with noweb
expansion, and then the long running block still runs every time. That
was a surprise to me, since nothing was changing in that block, so I
thought it would just use the cached result.


Greg Minshall <minshall@umich.edu> writes:

> John,
>
>> I tried this but it did not work for me.
>
> to be clear, caching means that the *first* time you execute, your
> reference will have to wait for the long-running computation to
> complete, but not during subsequent executions (unless the source block
> that performs the execution changes, in which case the reference will
> again have to wait).
>
> also, caching means that, after the first execution (ditto caveat) the
> source block *will no longer run*.  so, if there were any (other) side
> effects of running that source block, they will not happen.  (you could
> possibly split the side effect-producing code out of that block.)
>
> i'm not sure if this explains what did not work for you.
>
> cheers, Greg
>
>>
>>
>> On Wed, Jan 27, 2021 at 5:38 PM <tomas@tuxteam.de> wrote:
>>
>> > On Wed, Jan 27, 2021 at 05:14:43PM -0500, doltes wrote:
>> > > Get =#+RESULTS= without re-evaluating source code block?
>> > >
>> > > Let's suppose I have a code block which requires a long time to finish
>> > >
>> > > #+NAME: big-computation
>> > > #+begin_src bash
>> > > sleep 5 # Some computation which requires a long time to complete.
>> > > echo a
>> > > #+end_src
>> > >
>> > > #+RESULTS: big-computation
>> > > #+begin_example
>> > > a
>> > > #+end_example
>> > >
>> > > I want to use the results of that code block in other code blocks so I
>> > > use a =noweb= reference (see below.)
>> > >
>> > > #+begin_src bash :noweb yes
>> > > printf "%s\n" <<big-computation()>>
>> > > #+end_src
>> > >
>> > > #+RESULTS:
>> > > #+begin_example
>> > > a
>> > >
>> > > #+end_example
>> > >
>> > > However, doing this (i.e. using a =noweb= reference) would make the
>> > > command to be evaluated whenever getting its results. I don't want
>> > > this, I want the =:noweb= reference to actually use the already
>> > > computed results.
>> > >
>> > > So, my question is: Is it possible to use the actual =#+RESULTS= code
>> > > block instead of always evaluating it when referencing the results
>> > > through a =:noweb= reference?
>> >
>> > Perhaps "Cache results of evaluation" (15.5 Evaluating Code Blocks,
>> > in the Interwebs here [1] is for you.
>> >
>> > In short, add a header argument :cache yes to your code block.
>> >
>> > Cheers
>> >
>> > [1] https://orgmode.org/org.html#Evaluating-Code-Blocks
>> >
>> >  - t
>> >
>> --
>> John
>>
>> -----------------------------------
>> Professor John Kitchin
>> Doherty Hall A207F
>> Department of Chemical Engineering
>> Carnegie Mellon University
>> Pittsburgh, PA 15213
>> 412-268-7803
>> @johnkitchin
>> http://kitchingroup.cheme.cmu.edu


--
Professor John Kitchin
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
@johnkitchin
http://kitchingroup.cheme.cmu.edu


  reply	other threads:[~2021-02-02  2:11 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-27 22:14 doltes
2021-01-27 22:38 ` tomas
2021-01-27 23:31   ` John Kitchin
2021-01-28  3:26     ` Greg Minshall
2021-02-02  2:10       ` John Kitchin [this message]
2021-02-02 20:02         ` Nick Dokos
2021-01-27 23:33   ` doltes

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