[XeTeX] [tex-implementors] Proposal : that TeX engines generating PDF directly should be able to close the output file without terminating.

[Philip Taylor]

Jonathan Kew wrote:

> This raises the question of what state the TeX engine should return to 
> when the hypothetical \nextpdf primitive is executed. Does it return 
> to a pristine "initex" state, or a "freshly-loaded .fmt file" state, 
> or is the current state completely unchanged (does \jobname reflect 
> the new output name?), or what? Should the \count variables that are 
> by convention used to record page numbers get reset?
>
> Does a new .log file also get started? What about \write output files 
> -- are they flushed and new files started?
>
> It's true there would be a difference if there are macros etc. defined 
> while processing the first file, and then used while generating the 
> second. But I'm not sure this is really a commonly-required use case.
>
> Consider me not yet persuaded......

I think that "not yet persuaded" is a perfectly reasonable position when 
such a radical change has been proposed, but I remain completely 
unconvinced of the alleged benefits of so-called "use cases".  "Use 
cases" are only what we can think of today — tomorrow, someone may think 
of something totally different.  When considering whether an idea is a 
good one or not should not depend on whether or not one can find valid 
use cases for it — the idea should be considered solely on its merits.

With Jonathan's earlier points, I completely agree — I can envisage 
scenarios in which one would want to simply close the PDF file (having 
first flushed any pending insertions), open a new one and carry on.  I 
can also envisage scenarios in which one would want the engine to behave 
as if it had just been freshly launched.  I would therefore suggest that 
\newpdf be defined to inspect a mask variable (a count variable treated 
as a bit set) which a user could elect to set as he or she wishes, 
indicating which elements are to be carried over and which elements are 
to be re-set.

Philip Taylor