From Martin Maechler <maechler@stat.math.ethz.ch>  Wed Jul  1 11:26:17 1998
From: Martin Maechler <maechler@stat.math.ethz.ch> (Martin Maechler)
Date: Wed, 1 Jul 1998 12:26:17 +0200
Subject: "Coding conventions" for R:  Use  TRUE & FALSE, and not T & F
Message-ID: <199807011026.MAA18481@sophie.ethz.ch>

The reason being 
a design decision of a while ago
that "T" and "F"  shouldn't be reserved words in R as they are in S-plus.
Hence, T & F are just variables being set to TRUE and FALSE respectively;
they *can* be overwritten by the user which is very useful e.g.,
when you do
	  mydat <- read.table(file, header =TRUE)
and the file has variable names "T" or "F" and then do  attach(mydat).

Even more important is the situation when you have factors with levels
"T" or "F" which (I think to remember) is a pain in S.


-----------
Consequence
-----------
	 Package writers 
		(including R-core'ers incorporating other people's patches..):

	 *Please* always use  TRUE and FALSE

Kurt: Part of the above should definitely go into the 
	R-FAQ "Differences S & R"

Martin Maechler <maechler@stat.math.ethz.ch>			<><
Seminar fuer Statistik, ETH-Zentrum SOL G1;	Sonneggstr.33
ETH (Federal Inst. Technology)	8092 Zurich	SWITZERLAND
phone: x-41-1-632-3408		fax: ...-1086
http://www.stat.math.ethz.ch/~maechler/
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"Coding conventions" for R: Use TRUE & FALSE, and not T & F
Martin Maechler