[NTG-pdftex] \primitive\pdfoutput cannot be queried

Heiko Oberdiek oberdiek at uni-freiburg.de
Fri Apr 10 00:52:17 CEST 2009


Hello,

AFAIK, an expression with \primitive will become expandable
if and only if the primitive is expandable.
(pdfTeX: \pdfprimitive)

The problem arises with \pdfoutput, a kind of count register.
Therefore it isn't expandable. This doesn't hurt, if \pdfoutput
is set. However it cannot get its value anymore:

  \gdef\pdfoutput{\primitive\pdfoutput}

a) \ifcase\pdfoutput
   fails with
     ! Missing number, treated as zero.
     <to be read again> 
                        \primitive 

b) \ifcase\the\pdfoutput
   fails with
     ! You can't use `\primitive' after \the.

c) \ifcase\number\pdfoutput
   fails with
     ! Missing number, treated as zero.
     <to be read again> 
                        \primitive 

d) \count0=\pdfoutput
   fails with
     ! Missing number, treated as zero.
     <to be read again> 
                        \primitive 

Yours sincerely
  Heiko <oberdiek at uni-freiburg.de>


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