[texhax] dual-use input/output macro

Lars Madsen daleif at imf.au.dk
Thu Nov 17 21:54:00 CET 2005

Karl Berry :

> Suppose I want to show both the TeX input and its corresponding output
> as an example.  Not big files, but just small fragments.  As in:
>  \showme{hello, \relax there}
> and the typeset output could be, say, two lines:
>  hello, \relax there   % in typewriter
>  hello, there          % in roman
> I cannot think of any easy way to do this.  About all I can imagine is
> changing all the catcodes to other before reading the argument, printing
> the arg in tt, then writing the arg to an external file, and
> reading it back with normal catcodes to get the normal output.
> Is there a simpler way?  Has anyone programmed the above?  I imagine
> e-tex's \scantokens and \readfile (or something else?) might be useful,
> but didn't see a quick application.
> I browsed through the fancyvrb, verbatim, etc., doc but nothing jumped
> out at me.
> Just wondering :).
> k

There is of course the way lshort does it, i.e. write the argument to an 
external file, do a verbatim input and a normal input. I use the same 
thing for internal examples i my LaTeX book.

But there should be a rather exotic package by Peter Sabo (if it's spelled 
like that), I've forgotten the name, but he gave a talk about it at 
EuroTeX 2005.


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