>>>>> "Vincent" == Vincent Goulet <[EMAIL PROTECTED]>
>>>>> on Fri, 22 Apr 2005 16:56:45 -0400 writes:
Vincent> Le 22 Avril 2005 13:41, Liaw, Andy a écrit :
>> > From: bogdan romocea
>> >
>> > Great suggestion; it made me change all my Ts/Fs to
>> TRUE/FALSE. > Given > F <- TRUE > T <- FALSE > is
>> it possible to forbid T to stand for TRUE, and F for
>> FALSE in > function(...,something=T)? > Or,
>> alternatively, never allow F <- whatever and T <-
>> whatever?
>> >
>> > I don't know what the technical side is, but I think it
>> would be much > better if this particular blunder (major,
>> yet rather easy to overlook) > was impossible to make.
>>
>> R FAQ 3.3, bullet #3:
>>
>> In R, T and F are just variables being set to TRUE and
>> FALSE, respectively, but are not reserved words as in S
>> and hence can be overwritten by the user. (This helps
>> e.g. when you have factors with levels "T" or "F".)
>> Hence, when writing code you should always use TRUE and
>> FALSE.
>>
>> If T and F are changed as you suggested above, it will
>> break S compatibility in lots of code.
>>
>> Andy
Vincent> I think it used to be that the situation about
Vincent> T/TRUE and F/FALSE being preassigned/reserved was
Vincent> exactly the opposite between R and S-Plus.
no. that's not true, see below.
Vincent> However, in S-Plus 6.1.2 for Linux and S-Plus 6.2.1
Vincent> for Windows, TRUE and FALSE and still preassigned
Vincent> values of T and F, respectively, but one cannot
Vincent> redefine them. In other words, TRUE and FALSE are
Vincent> also reserved names in S-Plus.
That has always been the case.
Vincent> So, using TRUE and FALSE seems to be a common
Vincent> denominator for R and S-Plus (and a sensible
Vincent> choice, for that matter). That's what I teach my
Vincent> students.
and so ``should'' everyone else.
Vincent> Vincent
Vincent> -- Vincent Goulet, Associate Professor École
Vincent> d'actuariat Université Laval, Québec
Martin Maechler, ETH Zurich
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