G'day Brian,
>>>>> "BDR" == Prof Brian Ripley <[EMAIL PROTECTED]> writes:
BDR> On Fri, 2 Dec 2005, Berwin A Turlach wrote: [...]
>> The second behaviour that I cannot explain was produced by code
>> written by somebody else, namely:
[...]
>> The documentation of function() says that if "the end of a
>> function is reached without calling 'return', the value of the
>> last evaluated expression is returned." And this seems to
>> happen in this case:
BDR> Yes, but that value can be returned with R_Visible set to 0,
BDR> by calling invisible() _or otherwise_.
Thanks for the clarification. I had the sneaking suspicion that
something like this was happening, but couldn't find anything in the
documentation.
I vaguely remember that S has a mechanism to switch auto-printing
on/off via a variable, whose name started with ".", but couldn't find
anything in the blue book (by now I found .Auto.print in Suesselbeck
and VR "S programming). Since we don't have a license for S-plus
anymore, I couldn't check S-Plus and I didn't find anything similar in
R. I take it that R handles all this via R_Visible at the C level?
BDR> R does not print the value of a while() loop. [...] (Look
BDR> up the code of do_while for why.)
I can see that in the code of do_while the variable R_Visible is set
to zero, but there is no explanation for why this is done. But I
guess it is for compatibility reasons with S, since by now I found in
various books on the S language that the while() loop returns its
value invisible.
Thanks for adding the value section to the help page to clarify this
issue in the R documentation.
Cheers,
Berwin
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