From: Holger Hoefling <hhoeflin@gmail.com>
To: nicholas.dokos@hp.com
Cc: emacs-orgmode@gnu.org, Carsten Dominik <carsten.dominik@gmail.com>
Subject: Re: Not overwriting unchanged source code files when tangling
Date: Sat, 19 Nov 2011 07:58:24 +0100 [thread overview]
Message-ID: <CAFDswJsb41CHj5Fpyq9kSNNU-i=G9bMJ_fTyOvxtfKKa1cAbMw@mail.gmail.com> (raw)
In-Reply-To: <5462.1321675205@alphaville.dokosmarshall.org>
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Hey Nick,
thank you very much. That sounds like a very good solution to my problem
that does not require changes to org-mode.
Best
Holger
On Sat, Nov 19, 2011 at 5:00 AM, Nick Dokos <nicholas.dokos@hp.com> wrote:
> Holger Hoefling <hhoeflin@gmail.com> wrote:
>
> > I think you misunderstood me there - I am actually not worried about how
> > computationally intensive the tangling process is. This always works very
> > quickly, so even if they have to be copied around and take a bit longer,
> I
> > would not mind.
> >
>
> Ah, ok - so you are talking about
>
> tangle compile
> org -------> bunch of files -------------> output
>
> The tangling step produces a bunch of files that are (re)compiled (or in
> any case require some sort of lengthy processing) to produce some output
> file.
>
>
> IMO, the best way to deal with it is still make: let's say
>
> foo.org ----> a.x b.x c.x ------> foo.out
>
> where the first arrow is the tangle and the second arrow is some
> processor, call it X.
> The standard way to set up a makefile is schematically:
>
> --8<---------------cut here---------------start------------->8---
> foo.out: a.x b.x c.x
> X a.x b.c c.x -o foo.out
>
> a.x b.x c.x: foo.org
> tangle foo.org
>
> --8<---------------cut here---------------end--------------->8---
>
>
> Rewrite the make file as follows:
>
>
> --8<---------------cut here---------------start------------->8---
> foo.out: a.y b.y c.y
> X a.y b.y c.y -o foo.out
>
> a.y: a.x
> cmp --silent a.x a.y || cp a.x a.y
>
> b.y: b.x
> cmp --silent b.x b.y || cp b.x b.y
>
> c.y: c.x
> cmp --silent c.x c.y || cp c.x c.y
>
> a.x b.x c.x: foo.org
> tangle foo.org
> --8<---------------cut here---------------end--------------->8---
>
>
> So if the *contents* of (say) a.x have not changed by the tangling, it
> compares
> equal to a.y and the copy is skipped. That leaves a.y untouched.
>
> OTOH, if the contents of a.x change (or a.y does not exist in the first
> place), the comparison fails and we copy a.x to a.y. That updates a.y
> and forces further updates on anything that depends on it.
>
> Using some make fu (works for GNU make, but not necessarily for other
> makes),
> you can write it more compactly:
>
>
> --8<---------------cut here---------------start------------->8---
> foo.out: a.y b.y c.y
> X a.y b.y c.y -o foo.out
>
> %.y: %.x
> -cmp --silent $< $@ || cp $< $@
>
> a.x b.x c.x: foo.org
> tangle foo.org
> --8<---------------cut here---------------end--------------->8---
>
> HTH,
> Nick
>
>
>
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next prev parent reply other threads:[~2011-11-19 6:58 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-18 13:17 Not overwriting unchanged source code files when tangling Holger Hoefling
2011-11-18 14:23 ` Brian Wightman
2011-11-18 16:46 ` Tom Prince
2011-11-18 17:14 ` Brian Wightman
2011-11-18 14:27 ` Sebastien Vauban
2011-11-18 17:02 ` Carsten Dominik
2011-11-18 17:28 ` Brian Wightman
2011-11-18 19:42 ` Eric Schulte
2011-11-18 20:10 ` Achim Gratz
2011-11-18 20:24 ` Eric Schulte
2011-11-19 0:49 ` Holger Hoefling
2011-11-18 19:01 ` Holger Hoefling
2011-11-18 19:32 ` Nick Dokos
2011-11-19 0:51 ` Holger Hoefling
2011-11-19 4:00 ` Nick Dokos
2011-11-19 6:58 ` Holger Hoefling [this message]
2011-11-19 18:32 ` Holger Hoefling
2011-11-22 21:17 ` Allen S. Rout
2011-11-22 21:43 ` Nick Dokos
2011-11-19 18:06 ` cberry
2011-11-18 19:51 ` Achim Gratz
-- strict thread matches above, loose matches on Subject: below --
2011-11-19 15:31 Rustom Mody
2011-11-19 15:51 ` Rustom Mody
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