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

[mskala at ansuz.sooke.bc.ca]

On Thu, 1 Dec 2011, Philip TAYLOR wrote:
> > ! Unable to load picture or PDF file 'Resources/Images/TAR-2.tex'.
>
> and no
>
> > ! Unable to load picture or TeX file 'Resources/Images/TAR-2.tex'.

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 in order to conserve space
in the string table.  Rather than writing and storing two completely
separate strings for these two similar errors, one error message that
could apply to either of them was written and used for both.  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.

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.

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.
-- 
Matthew Skala
mskala at ansuz.sooke.bc.ca                 People before principles.
http://ansuz.sooke.bc.ca/