Re: Not overwriting unchanged source code files when tangling

[Holger Hoefling <hhoeflin@gmail.com>]

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Hi Nick,

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.

Thanks

Holger

On Fri, Nov 18, 2011 at 8:32 PM, Nick Dokos <nicholas.dokos@hp.com> wrote:

> Holger Hoefling <hhoeflin@gmail.com> wrote:
>
> > Hi Carsten,
> >
> > thanks for the suggestion, but as I agree with Brian. If there is more
> > than one source file in the org-file, then the whole project would
> > still be recompiled, not just the updated file.
> >
> > To be more exact, I actually don't want to compile things, but run R
> > scripts using make. So the waiting time if a computationally intensive
> > step is repeated although it is not necessary can be substantial.
> >
> > I wonder how difficult the following change would be (no emacs lisp
> experience, also do not know the org source code):
> >
> > - would it be possible to write out the source files when tangling
> > - into a temporary directory, then compare to the actual target files
> > - and overwrite only if something has changed? Then the time stamps
> > - would stay fixed. Hopefully, this would not involve too much work:
>
> You've lost right there unless there is a method to select *which* source
> blocks to tangle. IOW, the problem is not the *comparison* of the temp and
> actual
> target files, it is the *production* of the temp files themselves: that's
> the computationally expensive step and this method does nothing to
> alleviate
> that. Unless I'm missing something.
>
> Nick
>
> > - creating temporary files and remembering the mapping to true files
>
> > - tangling out as usual into temporary files (so probably little
> > - change there)
>
> > - compare temporary file to true file (does emacs already have a diff
> > - utility that could be used?)
>
> > - overwrite true file if any changes
>
> > - delete temporary files
>
>

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