[XeTeX] XeTeX, XeTeXpicfile, and counter-intuitive behaviour

[Philip TAYLOR]

mskala at ansuz.sooke.bc.ca wrote:

> It seems obvious to me that the command to load a PDF file and the command
> to load a picture are sharing an error message

I would agree with this.

> in order to conserve space

but reserve judgement on this.

> I've been
> programming for just under 30 years and certainly remember the days when
> string space was a precious enough commodity to necessitate such
> techniques; some people on this list may have even earlier memories.

I do indeed.  But this is 2011, and XeTeX is a new kid on the block;
surely we do not need to use 30-year old techniques when 64 bit processors
are already ubiquitous.

> Today, we may be able to afford another 50 bytes or so to give more
> specific error messages to each of two closely-related errors.  But note
> that adding another error message also means that any set of translated
> error messages also needs one more entry.  It costs more work than just
> the 50 bytes of storage.

And it cost me, and fellow members of this list, considerable work
to identify the problem.  Multiply that by the number of fellow
sufferers that must have hit this error message and been completely
mystified, as I was, and the overheads of translating one extra
error message vanish into insignificance.

> I don't think that the fact the picture command says it cannot load a PDF
> file when, in fact, it cannot, is cause for much comment.  And the fact it
> says it cannot load a picture or PDF file this time should not be taken as
> implying that that exact command might ever be able to load a PDF file
> at all.

I'm sure that Humpty Dumpty, M.E.P., would argue just that.  But for the
common man on the top deck of the Number 53 Clapham Common Omnibus,
a diagnostic that says :

	     ! Unable to load picture or PDF file

when it is called with the path to a non-existence JPG, and

	     ! Unable to load picture or PDF file

when it is called with the path to a most-definitely-existent PDF

must certainly be one of the most confusing things that he will have
encountered in his life.

Philip Taylor