[R] commenting demos

[Spencer Graves]

Could one use "cat" for comments, as: 

      cat("this is a comment that may survive 'source'\n")

??
hope this helps.  spencer graves

Martin Maechler wrote:

>>>>>>"Olivia" == Olivia Lau <olau at fas.harvard.edu>
>>>>>>    on Sun, 26 Oct 2003 00:49:45 -0400 writes:
>>>>>>            
>>>>>>
>
>    Olivia> Hi, Is there a way to make demo() print comments
>    Olivia> along with the code and output?
>
>not so easily.  The same applies to  example(.).
>Both demo(.) and example(.) end up calling source(.) which
>itself relies on
> 1)  parse(...)
> 2)  eval(...)
>
>parse(.) in R (currently) drops all comments, so they are "lost"
>very early in source() and hence everything else that calls source().
>
>Many have wanted a version of source() {and hence demo() and
>example() and ....} that would be able to echo all comments; but
>this is not really easy: Somehow you need a version of parse()
>{think of multiline statements!} to do this properly.
>
>    Olivia> For example, if I use something like
>    Olivia> readline("..."), demo prints both readline("...")
>    Olivia> and ...; as far as I can tell, this is also true of
>    Olivia> print() and cat().  I just want students to stop and
>    Olivia> think about every command in my demo scripts.
>
>One way, not using demo() would be to ask them to read the R
>script (e.g. in winedt or emacs) and *send* the commands to a
>running R themselves.
>
>But's that's a quite different approach {than demo()}.
>Martin
>
>Martin Maechler <maechler at stat.math.ethz.ch>	http://stat.ethz.ch/~maechler/
>Seminar fuer Statistik, ETH-Zentrum  LEO C16	Leonhardstr. 27
>ETH (Federal Inst. Technology)	8092 Zurich	SWITZERLAND
>phone: x-41-1-632-3408		fax: ...-1228			<><
>
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