[pdftex] pdftex deterministic?

[Matteo Centonza]

On Tue, 2007-04-03 at 15:09 +0200, Martin Schröder wrote:
> 2007/4/3, Matteo Centonza <matteo at metatype.it>:
> > Using checksums is the cheapest way of comparing two files
> > (even cheaper than a byte comparison) and give you absolute
> > confidence on the result.
> >
> > The only drawback is that you have to slightly modify the driver
> > in order to make this possible (e.g. fixing IDs differences)
> > but this could be an explicit option given to pdftex to let
> > it strip runtime info and focalize on the content. For
> > final production files you have simply to rerun pdftex
> > with this options turned off.
> 
> You can do this now if you reset your system date for each run of
> pdftex -- but I agree that that's not very practical.
> 
> The problem with comparing pdfs by byte is that in the end you don't
> want compatibility by byte: You want identical output and you don't
> care if e.g. the fonts have a different way of being subsetted. And
> the only way to test for identical output is to rip the pdfs and
> compare the resulting files.

hi Martin,

i have only a working experience on dvipsk, but so far, if fonts
are differently subsetted, then there's a discrepancy between the two
files (I'm assuming that the two files are generated by the same binary
application, as this is my case, just two different latex files).

I've not yet verified if pdf behaves the same. Time will tell ;)

Cheers,

-m

> Best
>    Martin
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