Ignoring pdftex primitives (Re: BOUNCE pdftex@tug.org: Non-member submission from [Michael John Downes <mjd@ams.org>])

[Sebastian Rahtz]

From: Michael John Downes <mjd at ams.org>


> No, things like
> \pdfimage height 3 cm height 2 cm depth 1cm height 5cm picture.png
> are perfectly valid (as with \hrule and \vrule in ordinary TeX),
> the later ones overriding the earlier ones.

Following the hrule/vrule syntax is probably not a good idea in the
first place and when a file name follows I think that this is
definitely a design mistake, as Howlett's example demonstrates. The
two most likely alternatives (while still remaining close to TeX)
would be

  \pdfimage filename <space> <width-height-depth spec> ... (repeatable)

I.e., put the file name first and require it to be terminated by a
space. Then the whole construct is syntactically similar to \vrule and
\font in the handling of trailing tokens (still not exactly a good
idea ...)

Or:

  \pdfimage <width-height-depth spec> ... from filename <space>

I.e., introduce a new mandatory keyword "from". Compare to the
mandatory "to" in \read\x to\y.

Space must be accepted as a filename terminator if you want to follow
the example of \input. Better, however, would be to devise a different
filename syntax for all filename handling and leave \input etc as
deprecated but still working alternatives. I.e., make some new file
handling primitives:

1. \interject{File Name}

Same as \input, but argument is enclosed in braces. This allows file
names to include spaces. The main trouble here is deciding on the
command name. [... goes off to consult a dictionary ...] 
\interleave, \interject, \incorporate, \interpolate, \intercalate,
\digress.

Inject, interject, or intercalate are semantically the best matches
for what TeX actually does when inputting a file. Intercalate is
rarely heard outside of academic contexts.  The primary meaning for
inject in common usage is the medical meaning. So I would probably
choose "interject".

2. \openfile read 5{File Name}
   \openfile write 8{File Name}

These are replacements for \openout and \openin with syntax similar to
\hbox to 5pt{...} or \write 16{...}. Naming: Maybe \fileopen instead
of \openfile.  Maybe keywords "in" "out" instead of read/write.

3. \fontdef\foo{cmr10}
   \fontdef\bar at 24pt{cmr17}
   \fontdef\baj scaled 1200{cmbxti10}

Like \font but allows spaces in font file names.

Then probably, as was already suggested:

4. \pdfimage height 3cm {File Name}

with height/depth/width specs going before the open brace.

Speaking as a TeX macro writer with many years of experience, having
1-3 above would have saved me many puzzling moments and a lot of extra
work over the years to save users from unnecessary or unapropos error
messages.

Note that it is still possible to use unmatched { } characters in a
file name as long as you make sure they don't have catcode 1 or 2. For
example:

  \interject{Foo\string{bar}

(File names must be processed with full expansion, like \special or
\edef; so this is similar to \edef\foo{Foo\string{bar} (a valid TeX
3.x assignment).)

Michael Downes