Re: PDF automatic deletion unnecessary in Windows

[Mats Bengtsson]

Nathan Reed wrote:
> Hello,
>
> Following the resolution of issue #635 a couple of years ago[1], the behavior of
> Lilypond in Windows has been to delete the old PDF file before trying to
> generate PDF output from PS.  The understanding seemed to be that deleting the
> old file is problematic in Linux, but necessary in Windows.  I do not think it
> is necessary in Windows either.
>
> I'm using Lilypond 2.12.3 on Windows XP SP1 and viewing my PDFs with Sumatra
> 1.0.1.  As discussed on the Sumatra forums[2], Sumatra opens the file in such a
> way that it can be overwritten, but not deleted.  Therefore lilypond fails
> whenever the PDF is open in Sumatra.  However, removing the deletion
> (backend-library.scm, lines 114-115) fixes the issue.  Lilypond happily
> overwrites the PDF and Sumatra reloads it.
>
> Most other PDF viewers, such as Adobe Reader, open the file in a way preventing
> even overwriting.  So for these there is no hope of being able to update the PDF
> at all while the file is open, whether by deleting the file or not.  So I don't
> believe this change would break any existing behavior, but would fix the
> behavior with Sumatra.
>   
Makes sense!

However, it would be very interesting if anybody could figure out what 
kind of trick recent versions of WinEdt use when they process LaTeX 
files, and are able to update a PDF file that is open in Acrobat and 
automatically reload the updated version in Acrobat. Clearly, somebody 
has found a very clever solution that would be very useful for us as well.

  /Mats