🚀 go-pugleaf

Glenn Reid writes:
> The end-of-file (it isn't always a ^D) is echoed by the printer when
> an EOF is read from the input stream.
and
> I think the EOF is echoed then, by the scanner, rather than after the
> "showpage" name has been executed, but I'm not sure of it. In any
> case, it is an implementation detail.
and much else in the same vein.

I suppose it is foolish of me to argue with someone from Adobe about
their own software, but I think Glenn is just plain wrong about this.
The ^D (EOT) character is sent *from* the printer as part of the
server loop, in the finish-off-the-current-job code, before it starts
to think about where to get the next job from. Reaching the EOT in
the input buffer just causes the scanner (or anyone else reading
"currentfile") to see end-of-file (and you can't get past it, at least,
not without trickery). Nothing is sent from the printer at this stage.

As Glenn points out, if this wasn't the case then the ^D's wouldn't
properly delimit the error messages produced by different jobs, and
in fact they do. (I suppose I should add: on a LaserWriter, rev 0 or
2; but surely this can't be a matter of different implementations on
different printers?)

As others have pointed out, it would be unwise to assume that the
^D from the printer meant "I have printed that job perfectly" rather
than "I have told you all I am ever going to tell you about that job",
but at least it does mean the latter.

Chris Thompson
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