[texhax] Strange \loop-behaviour

[Reiner Durchholz]

This is a report of what I believe is a flaw in the "\loop"  
implementation.
The appended source text behaves differently with and without the  
\null-command.
Instead of \null, almost any other command can be used.
The flaw came to my attention when I first used a \showthe for error  
analysis.

The used system is OS X 10.5.5.
The TeX system is TeXShop V2.26 with  XeTeXk, Version  
3.1415926-2.2-0.999.6 (Web2C 7.5.7)

%!TEX TS-program = xetex
%!TEX encoding = UTF-8 Unicode
\parindent=0cm
% ______________________________________________________
\openin1=TestObject
\newcount\more \more=1 % used as boolean, set to "true"
% -----------------------------------------
\loop
\read 1 to \InputLine
\ifeof1\more=0\fi
\null % without this command, the loop either does not end or ends  
immediately
\number\more
\ifnum\more=1
  -- \InputLine\ +++ \hfil\break
\repeat
% -----------------------------------------
\closein1
\bye



  -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- - -- -- --  
-- -- -- - -- -- -- -- -- -- --
   Dr. Reiner Durchholz
  -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- - -- -- --  
-- -- -- - -- -- -- -- -- -- --





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